Baltic Sea

Summary

The physical disturbance pressures from mobile bottom-contacting fishing gears is spatially constrained in the Baltic Sea region with 27% of the grid cells (I-2), and 12% of the surface area (I-3), in the depth zone 0-200m, being fished on average per year for the period 2013-2018 (Table 1). Fishing is very aggregated with 90% of the pressure occurring in 8% of grid cells (I-4).

The PD method shows an average decline in community biomass of 1% relative to carrying capacity across c-squares (I-6). All c-squares (100% (I-7)), have an impact score less than 20%. The L1 method shows an average impact of 0.12 across c-squares (I-6). The majority of c-squares, 85% (I-7), have impact scores less than 20% (I-7).

Maps of spatial distribution of intensity (surface abrasion), seafloor sensitivity and economic value and weight of fisheries landings are shown in Figure 1.

Table 1

Table 1. Pressure and impact indicators for 2013-2018
Indicators	0 to 200 m	200 to 800 m	more than 800 m
Average intensity (I-1)	0.31	0	NA
Proportion of area in fished cells (I-2)	0.27	0	NA
Proportion of area fished per year (I-3)	0.12	0	NA
Smallest prop. of area in fished cells with 90% of fishing effort (I-4)	0.08	NA	NA
Proportion of area in unfished cells (I-5)	0.73	1	NA
Average PD impact (I-6)	0.01	0	NA
Average L1 impact (I-6)	0.12	0	NA
Proportion of area with PD impact < 0.2 (I-7)	1.00	1	NA
Proportion of area with L1 impact < 0.2 (I-7)	0.85	1	NA

Figure 1

Figure 1 Geographic distribution of surface abrasion, seabed sensitivity (community longevity) and total value and weight from mobile bottom-contacting gear. The maps of surface abrasion, value and weight show the average per year for 2013-2018

Pressure

The distribution of fishing intensity in the Baltic Sea is very localized (Figure 2). Areas of higher intensity occur in the south-western Baltic Sea (the south of the Baltic Proper, the Arkona and Bornholm basins). All other basins of the Baltic Sea are virtually unfished.

The proportion of area subject to fishing pressure differs between broad-scale habitats and is highest in offshore circalittoral sand (75% of grid cells fished) and offshore circalittoral mud (62% of grid cells fished) (Table 2). The broad-scale habitats with the highest fishing intensity are: offshore circalittoral sand (average intensity = 1.78 year-1) and offshore circalittoral mud (average intensity = 1.62 year-1).

Figure 3 shows the fishing intensity for the four largest MSDF broad-scale habitats. Total fishing intensity peaked in 2012, and has been steadily decreasing since then (Figure 3). This trend is driven by the fishing intensity circalittoral sand and circalittoral mud, with the fishing intensity in the other areas being relatively stable over time (Figure 3). The average trawling intensity is more variable over time than the proportion of area fished (Figure 3, compare left and middle panel). This shows that changes in intensity have not affected the spatial distribution of the footprint much.

Fishing pressure is highly aggregated, both at the regional level as well as at the level of the habitat (Figure 3, right panel). The smallest proportion of habitat with 90% of effort is less than 10%. The intensively fished areas represent the ‘core fishing grounds’. These grounds contribute most of the landings and value (Figure 4). Almost 90% of the fishing effort (swept area), landings and value, occur in only 10% of the surface area of the Baltic Sea (Figure 4).

Figure 2

Figure 2 Surface abrasion, Swept Area Ratio, by mobile bottom-contacting gears (year-1), averaged for the 2013-2018 six-year cycle

Table 2

Table 2 Overview of pressure indicators of all mobile bottom-contacting gears per broad-scale habitat averaged for 2013-2018. I refers to the indicators in Table 1.
MSFD broad habitat type	Extent of habitat (1000 km²)	Number of grid cells	Landings 1000 tonnes	Value 10⁶ euro	Swept area 1000 km²	Average intensity (I-1)	Prop. of area in fished grid cells (I-2)	Prop. of area fished per year (I-3)	Smallest prop. of area with 90% of fishing effort (I-4)
Offshore circalittoral mud	21.14	2516	14.80	11.99	34.29	1.62	0.61	0.51	0.22
Offshore circalittoral mixed sediment	19.52	2969	7.39	6.93	21.07	1.08	0.43	0.27	0.10
Circalittoral sand	32.99	6544	6.32	5.42	15.99	0.48	0.46	0.22	0.08
Infralittoral sand	23.81	3837	3.33	3.06	11.02	0.46	0.56	0.22	0.10
Circalittoral mud	22.74	5777	5.20	4.90	10.84	0.48	0.29	0.19	0.05
Circalittoral mixed sediment	106.85	13549	5.50	3.10	5.94	0.06	0.13	0.03	0.03
Offshore circalittoral sand	2.74	770	1.84	1.63	4.89	1.78	0.75	0.52	0.22
Circalittoral mud or Circalittoral sand	53.88	7758	3.80	2.25	4.46	0.08	0.17	0.06	0.03
Offshore circalittoral mud or Offshore circalittoral sand	33.82	3094	1.23	0.97	2.77	0.08	0.24	0.06	0.06
Infralittoral mixed sediment	18.60	5537	0.47	0.77	0.85	0.05	0.16	0.03	0.03
Infralittoral mud	1.66	1205	0.30	0.35	0.69	0.41	0.40	0.19	0.05
Infralittoral coarse sediment	6.90	2429	0.28	0.27	0.51	0.07	0.28	0.05	0.06
Circalittoral coarse sediment	12.21	4661	0.41	0.23	0.50	0.04	0.19	0.03	0.04
Circalittoral rock and biogenic reef	6.84	3326	0.04	0.02	0.05	0.01	0.05	0.01	0.01
Infralittoral rock and biogenic reef	3.95	2296	0.01	0.01	0.04	0.01	0.08	0.01	0.01
Infralittoral mud or Infralittoral sand	3.87	1507	0.07	0.09	0.02	0.01	0.03	0.01	0.01
Offshore circalittoral coarse sediment	0.72	533	0.01	0.01	0.02	0.02	0.14	0.02	0.02
Offshore circalittoral rock and biogenic reef	0.18	231	0.00	0.00	0.00	0.00	0.02	0.00	0.02
Unknown	0.18	100	0.00	0.00	0.00	0.00	0.00	0.00	NA

Figure 3

Figure 3. Time series of (a) mean fishing intensity (surface abrasion), (b) proportion of the surface area of the seafloor fished, (c) aggregation of fishing (proportion of the surface area with 90% of the fishing effort) by habitat. Results represent vessels over 15m (2009-2011) and vessels over 12m (2012-2018).

Figure 4

Figure 4. Cumulative proportion of the swept area, landings and value. Grid cells were sorted from highest to lowest fishing intensity and include non-fished cells. The results are for all mobile bottom-contacting gears based on averaged fishing data per c-square from 2013-2018.

Core fishing grounds

Core fishing grounds are defined as the c-squares with the 90% highest value of landings in the VMS data. Figure 5 shows the number of years c-squares are within the 90% highest value by métier. Only three métiers are used in the Baltic Sea: otter trawls for cod and plaice (OT_DMF) and for small pelagic fish (OT_SPF), and seine for plaice and cod (SDN_DMF). If fishing in a métier occurs in the same c-square every year with high value of landings, the rightmost bar in Figure 5 will be high, meaning that the c-square is within the 90% highest value of landings every year during the period 2013-2018. If a c-square is only within the 90% highest value in one year, it will end up in the bar at the left. Figure 6 shows the percentage area overlap between the 90% highest value per year and the reference fishing ground. Both figures highlight that the fisheries for small pelagic fish (OT_SPF) and the seine (SDN_DMF) have the highest variation in space.

Figure 7 illustrates the relationship between area fished in percent and the cumulated value of landings, sorted from the c-squares with highest value fisheries. The curves are generally starting steeply, illustrating the concentration of the fisheries at fishing grounds and the curves are ending horizontally, illustrating the peripheral fisheries going on outside the main fishing grounds.

Figure 8 shows the area associated with each 10-percentile interval for each métier using averages of SAR (left column) and landings value (euro, right column) for the period 2013-2018.

Figure 5

Figure 5. Number of years c-squares are within the 90% highest value by métier, presented as a % relative to the total number of c-squares (n) that are within the 90% highest value by métier across all years. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 6

Figure 6. Percentage area overlap between the 90% highest value per year and the reference core fishing ground. For métiers that are included in Figure 5 and missing in Figure 6, no reference core ground could be established and/or métiers were not used in the area in some years.

Figure 7

Figure 7. Percent area fished vs. landings value (euro) by métier, coloured by year. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 8

Figure 8. The area associated with each 10-percentile interval for each métier using averages of SAR (left column) and landings value (euro, right column) for the period 2013-2018. The lightest blue c-squares represent the lowest 10% of total SAR / value of landings. The brown c-squares represent the highest 10% of total SAR / value of landings.

Fishing by métier

Intensity, weight and value of landings are estimated for the grid cells that were fished by one MBCG métier, ignoring cells fished by other métiers (Table 3).

The métier with the highest landings and value per area fished is the dredge trawl fishery for scallop (DRB_MOL) but note that only a very small area has been fished by this métier. The seines (SDN_DMF and SSC_DMF) have the lowest landings and value per area fished. This is followed by otter trawls that target cod and plaice (OT_DMF).

Table 3

Table 3. Overview of area fished (sum of swept area), landings and value for the different metiers. Area fished in 1000 km², weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Area swept (1000 km2)	<0.005	<0.005	105.79	0	3.25	5.09	0.02	0	0	0
Landings (1000 tonnes)	0.05	0.01	41.49	0	9.24	0.40	<0.005	0	0	0
Value (10^6 euro)	<0.005	<0.005	39.10	0	2.84	0.57	<0.005	0	0	0
Landings (1000 tonnes)/Area swept (1000 km2)	2133.71	3.61	0.39	NaN	2.84	0.08	0.05	NaN	NaN	NaN
Value (10^6 euro)/Area swept (1000 km2)	85.35	1.48	0.37	NaN	0.87	0.11	0.08	NaN	NaN	NaN

Impact

The impact of mobile bottom-contacting fishing from the PD method shows the areas of highest fishing impact in the southern part of the Baltic Proper (Figure 9, left). High impact from the L1 method covers a much larger area (Figure 9, right) that mimics the map of fishing intensity.

The impact scores are largely constant over time (Figure 10, left panel). Impact varies between habitats (Figure 9 shows the four most extensive habitat types). Of these four habitat types, impact is highest in circalittoral sand and lowest in offshore circalittoral mud/sand. All habitat types (100%) have a PD impact score <0.2, whereas more than 70% of each habitat type has an L1 impact score <0.2.

Table 4 shows impact per métier relative to weight and value of landings. In this analysis, the different métiers are assessed for the grid cells that were fished by one MBCG métier, ignoring cells fished by other métiers. As such this estimates the maximum impact compared to the untrawled situation and the impact estimated assuming all other métiers to have impacted the habitat will be less than this. The métier with the highest impact (PD and L1) relative to the value and landings is the seine trawl fishery for cod, haddock and flatfish (SSC_DMF). The dredge fishery for scallops (DRB_MOL) has the lowest impact per value and landings but note that only a very small area has been fished by this métier (Table 3).

Métiers differ in their habitat association and impact on each habitat type (Figure 11). Fishing impact on all broad-scale habitats are dominated by the otter trawl fishery (OT_ DMF). All other fisheries have little impact. The two impact indicators are typically showing similar qualitative patterns.

Figure 9

Figure 9. Impact of mobile bottom-contacting gears averaged for the 2013-2018 six-year cycle for the PD and L1 method.

Figure 10

Figure 10. The mean impact of mobile bottom-contacting gears in all combined MSFD habitats and the four most extensive habitat types between 2009 and 2018 (left). The proportion of the fished area with an impact of less than 0.2 (right)

Table 4

Table 4. Overview of impact per metier relative to weight and value of landings estimated for the grid cells fished (SAR >0) with these métiers only. Weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Landings (1000 tonnes)/PD impact	34.438	0.437	0.338	NA	3.555	0.151	0.052	NA	NA	NA
Value (10^6 euro)/PD impact	1.378	0.179	0.318	NA	1.092	0.215	0.081	NA	NA	NA
Landings (1000 tonnes)/L1 impact	39.745	0.525	0.018	NA	0.055	0.005	0.001	NA	NA	NA
Value (10^6 euro)/L1 impact	1.590	0.215	0.017	NA	0.017	0.007	0.001	NA	NA	NA

Figure 11

Figure 11. PD impact (upper panel) and L1 impact (lower panel) of selected gear groupings on the most extensive MSFD habitat types. Impact is estimated in isolation of the other gear groupings. Note the different scales on the Y-axis.

Management scenarios

The figures and tables below show one implementation of multi-purpose habitat management through reductions in effort and spatial closures for the four most extensive MSFD habitat types. They show the changes in average impact (PD, L1), unfished area and fisheries values of landings based on a static assessment of effort removal.

The analysis is based on the progressive removal of 5 to 99% of all MBCG fishing effort, starting from the c-squares with the lowest effort (corrected for the areal extent of the MSFD habitat within each c-square). Blue dots show the current situation and are used as reference. The % of unfished area in the reference is only based on grid cells that are unfished. Average PD and L1 impacts are a weighted average and consider the areal extent of each MSFD habitat type within a grid cell.

Note that the fraction of grid cells above/below a certain impact threshold initially remains the same (not shown) as the removal of effort starts from the c-squares with the lowest effort that typically have low impact.

MSFD habitat - 1

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.03	0.47	38.56	100.00	100.00
5	0.03	0.40	54.71	94.50	94.32
10	0.03	0.35	61.74	88.78	88.92
15	0.03	0.30	67.35	82.83	83.58
20	0.02	0.27	71.48	77.15	78.36
30	0.02	0.21	77.98	65.94	68.16
40	0.02	0.16	82.92	55.96	59.03
60	0.01	0.09	90.28	37.16	38.95
80	0.01	0.04	96.07	18.60	18.57
99	0.00	0.00	99.93	1.26	1.17

MSFD habitat - 2

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.02	0.26	57.31	100.00	100.00
5	0.02	0.22	76.31	94.67	92.96
10	0.02	0.19	80.57	89.97	87.92
15	0.02	0.16	83.26	85.13	82.64
20	0.02	0.14	85.59	79.95	77.49
30	0.01	0.11	88.80	70.12	67.59
40	0.01	0.08	91.76	60.51	57.80
60	0.01	0.04	95.94	40.66	39.07
80	0.00	0.01	98.77	21.02	21.05
99	0.00	0.00	100.00	1.91	2.00

MSFD habitat - 3

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.01	0.22	53.90	100.00	100.00
5	0.01	0.19	75.50	93.82	93.65
10	0.01	0.16	80.47	88.33	87.71
15	0.01	0.14	83.97	83.06	82.24
20	0.01	0.12	86.29	77.59	76.28
30	0.01	0.09	90.10	66.80	63.59
40	0.01	0.07	92.88	56.88	53.71
60	0.00	0.04	96.24	38.62	33.65
80	0.00	0.01	98.76	20.23	16.13
99	0.00	0.00	100.00	2.02	1.77

MSFD habitat - 4

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.01	0.22	43.80	100.00	100.00
5	0.01	0.19	71.50	88.50	87.41
10	0.01	0.16	78.26	80.33	80.45
15	0.01	0.14	83.12	73.08	72.67
20	0.01	0.12	86.18	66.53	66.89
30	0.01	0.08	90.25	50.32	50.08
40	0.00	0.06	93.07	40.78	39.27
60	0.00	0.03	96.82	23.08	21.26
80	0.00	0.01	99.03	11.03	10.09
99	0.00	0.00	100.00	2.98	1.73

Overview all MSFD habitats

Fishing effort consequences, as a % relative to total swept area, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Offshore circalittoral mud	21.14	0.0	0.0	0.0	0.0	<0.1	2.6	9.0	18.2	34.2	59.1
Offshore circalittoral mixed sediment	19.52	0.0	0.0	0.0	0.0	0.0	0.0	<0.1	1.3	9.2	34.1
Circalittoral sand	32.99	0.0	0.0	0.0	0.0	0.0	0.0	0.2	1.9	9.3	29.6
Infralittoral sand	23.81	0.0	0.0	0.0	0.0	0.0	0.1	1.0	4.2	11.8	29.5
Circalittoral mud	22.74	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	2.4	26.4
Circalittoral mixed sediment	106.85	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.5
Offshore circalittoral sand	2.74	0.0	0.0	0.0	<0.1	1.1	4.2	11.8	25.0	46.0	71.6
Circalittoral mud or Circalittoral sand	53.88	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	1.8
Offshore circalittoral mud or Offshore circalittoral sand	33.82	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.2	6.2
Infralittoral mixed sediment	18.6	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	1.6
Infralittoral mud	1.66	0.0	0.0	0.0	0.0	0.0	0.0	0.0	1.1	9.2	30.2
Infralittoral coarse sediment	6.9	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	1.3	10.9
Circalittoral coarse sediment	12.21	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	3.9
Circalittoral rock and biogenic reef	6.84	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral rock and biogenic reef	3.95	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud or Infralittoral sand	3.87	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral coarse sediment	0.72	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	2.0
Offshore circalittoral rock and biogenic reef	0.18	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Unknown	0.18	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Fishing value consequences, as a % relative to total value, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Offshore circalittoral mud	21.14	0.0	0.0	0.0	0.0	<0.1	3.0	10.1	20.9	38.3	62.2
Offshore circalittoral mixed sediment	19.52	0.0	0.0	0.0	0.0	0.0	0.0	<0.1	1.8	9.2	34.3
Circalittoral sand	32.99	0.0	0.0	0.0	<0.1	<0.1	<0.1	0.3	2.4	10.8	33.0
Infralittoral sand	23.81	0.0	0.0	0.0	0.0	0.0	0.4	2.0	10.1	22.4	48.8
Circalittoral mud	22.74	0.0	0.0	<0.1	<0.1	<0.1	<0.1	<0.1	<0.1	3.5	29.7
Circalittoral mixed sediment	106.85	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.8
Offshore circalittoral sand	2.74	0.0	0.0	0.0	0.1	1.5	5.3	14.2	27.2	47.1	71.4
Circalittoral mud or Circalittoral sand	53.88	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	4.2
Offshore circalittoral mud or Offshore circalittoral sand	33.82	0.0	0.0	0.0	0.0	0.0	<0.1	<0.1	<0.1	1.3	9.5
Infralittoral mixed sediment	18.6	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	2.3
Infralittoral mud	1.66	0.0	0.0	0.0	0.0	0.0	0.0	0.0	1.4	10.1	33.8
Infralittoral coarse sediment	6.9	0.0	0.0	0.0	0.0	0.0	<0.1	<0.1	<0.1	2.4	15.3
Circalittoral coarse sediment	12.21	0.0	0.0	0.0	0.0	<0.1	<0.1	<0.1	<0.1	<0.1	5.8
Circalittoral rock and biogenic reef	6.84	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral rock and biogenic reef	3.95	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud or Infralittoral sand	3.87	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral coarse sediment	0.72	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	5.9
Offshore circalittoral rock and biogenic reef	0.18	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Unknown	0.18	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Fishing weight consequences, as a % relative to total weight, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Offshore circalittoral mud	21.14	0.0	0.0	0.0	0.0	0.1	3.3	10.1	19.9	35.7	60.5
Offshore circalittoral mixed sediment	19.52	0.0	0.0	0.0	0.0	0.0	0.0	0.3	3.4	11.1	36.9
Circalittoral sand	32.99	0.0	0.0	0.0	<0.1	<0.1	<0.1	0.5	2.9	11.4	36.2
Infralittoral sand	23.81	0.0	0.0	0.0	0.0	0.0	0.4	2.3	11.4	22.7	49.2
Circalittoral mud	22.74	0.0	0.0	<0.1	<0.1	<0.1	<0.1	<0.1	<0.1	6.1	32.8
Circalittoral mixed sediment	106.85	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	1.1
Offshore circalittoral sand	2.74	0.0	0.0	0.0	0.1	1.9	5.7	13.5	25.7	46.7	70.8
Circalittoral mud or Circalittoral sand	53.88	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	5.2
Offshore circalittoral mud or Offshore circalittoral sand	33.82	0.0	0.0	0.0	0.0	0.0	0.2	0.2	0.2	5.1	25.4
Infralittoral mixed sediment	18.6	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	2.5
Infralittoral mud	1.66	0.0	0.0	0.0	0.0	0.0	0.0	0.0	1.8	11.5	35.7
Infralittoral coarse sediment	6.9	0.0	0.0	0.0	0.0	0.0	<0.1	<0.1	<0.1	2.1	14.0
Circalittoral coarse sediment	12.21	0.0	0.0	0.0	0.0	<0.1	<0.1	<0.1	<0.1	<0.1	5.4
Circalittoral rock and biogenic reef	6.84	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral rock and biogenic reef	3.95	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud or Infralittoral sand	3.87	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral coarse sediment	0.72	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	20.3
Offshore circalittoral rock and biogenic reef	0.18	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Unknown	0.18	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Bothnian area

Summary

The physical disturbance pressures from mobile bottom-contacting fishing gears is spatially constrained in the Bothnian subdivision with 6% of the grid cells (I-2), and 1% of the surface area (I-3), in the depth zone 0-200m, being fished on average per year for the period 2013-2018 (Table 1). Fishing is very aggregated with 90% of the pressure occurring in 1% of grid cells (I-4).

The PD method shows an average decline in community biomass of 0% relative to carrying capacity across c-squares (I-6). All c-squares (100% (I-7)), have an impact score less than 20%. The L1 method shows an average impact of 0.01 across c-squares (I-6). The majority of c-squares, 99% (I-7), have impact scores less than 20% (I-7).

Maps of spatial distribution of intensity (surface abrasion), seafloor sensitivity and economic value and weight of fisheries landings are shown in Figure 1.

Table 1

Table 1. Pressure and impact indicators for 2013-2018
Indicators	0 to 200 m	200 to 800 m	more than 800 m
Average intensity (I-1)	0.01	0	NA
Proportion of area in fished cells (I-2)	0.06	0	NA
Proportion of area fished per year (I-3)	0.01	0	NA
Smallest prop. of area in fished cells with 90% of fishing effort (I-4)	0.01	NA	NA
Proportion of area in unfished cells (I-5)	0.94	1	NA
Average PD impact (I-6)	0.00	0	NA
Average L1 impact (I-6)	0.01	0	NA
Proportion of area with PD impact < 0.2 (I-7)	1.00	1	NA
Proportion of area with L1 impact < 0.2 (I-7)	0.99	1	NA

Figure 1

Figure 1 Geographic distribution of surface abrasion, seabed sensitivity (community longevity) and total value and weight from mobile bottom-contacting gear. The maps of surface abrasion, value and weight show the average per year for 2013-2018

Pressure

The distribution of fishing intensity in the Bothnian subregion is very patchy (Figure 2). The few fished areas show very low levels of intensity.

The proportion of area subject to fishing pressure differs between broad-scale habitats and is highest in offshore circalittoral sand or offshore circalittoral mud (15% of grid cells fished) (Table 2). The broad-scale habitats all show very low average fishing intensities (< 0.02 yr-1).

Figure 3 shows the fishing intensity for the four largest MSDF broad-scale habitats. Total fishing intensity has been very stable over time (Figure 3). The average trawling intensity is more variable over time than the proportion of area fished (Figure 3, compare left and middle panel). This shows that changes in intensity have not affected the spatial distribution of the footprint much.

Fishing pressure is highly aggregated, both at the regional level as well as at the level of the habitat (Figure 3, right panel). The smallest proportion of habitat with 90% of effort is less than 5%. The intensively fished areas represent the ‘core fishing grounds’. These grounds contribute most of the landings and value (Figure 4). Fully 100% of the fishing effort (swept area), landings and value, occur in only 5% of the surface area of the Baltic Sea (Figure 4).

Figure 2

Figure 2 Surface abrasion, Swept Area Ratio, by mobile bottom-contacting gears (year-1), averaged for the 2013-2018 six-year cycle

Table 2

Table 2 Overview of pressure indicators of all mobile bottom-contacting gears per broad-scale habitat averaged for 2013-2018. I refers to the indicators in Table 1.
MSFD broad habitat type	Extent of habitat (1000 km²)	Number of grid cells	Landings 1000 tonnes	Value 10⁶ euro	Swept area 1000 km²	Average intensity (I-1)	Prop. of area in fished grid cells (I-2)	Prop. of area fished per year (I-3)	Smallest prop. of area with 90% of fishing effort (I-4)
Circalittoral mud or Circalittoral sand	28.12	4037	1.56	1.28	0.59	0.02	0.10	0.02	0.02
Circalittoral mixed sediment	55.99	6677	0.53	0.75	0.23	0.00	0.05	0.00	0.02
Infralittoral mixed sediment	4.86	2088	0.10	0.41	0.06	0.01	0.04	0.01	0.01
Circalittoral mud	3.22	2100	0.14	0.22	0.06	0.02	0.10	0.02	0.02
Circalittoral sand	7.33	2017	0.06	0.20	0.04	0.01	0.03	0.01	0.01
Circalittoral coarse sediment	3.25	1998	0.05	0.03	0.02	0.01	0.06	0.00	0.02
Infralittoral mud or Infralittoral sand	0.47	609	0.02	0.08	0.01	0.03	0.08	0.02	0.03
Infralittoral sand	0.83	480	0.02	0.06	0.01	0.01	0.04	0.01	0.02
Infralittoral coarse sediment	0.52	411	0.01	0.03	0.00	0.01	0.06	0.01	0.01
Circalittoral rock and biogenic reef	1.91	1349	0.00	0.00	0.00	0.00	0.01	0.00	0.01
Infralittoral mud	0.09	280	0.00	0.00	0.00	0.00	0.00	0.00	0.01
Offshore circalittoral mud or Offshore circalittoral sand	0.01	11	0.00	0.00	0.00	0.00	0.15	0.00	0.18
Infralittoral rock and biogenic reef	1.33	935	0.00	0.00	0.00	0.00	0.00	0.00	0.01
Offshore circalittoral mixed sediment	0.07	21	0.00	0.00	0.00	0.00	0.05	0.00	0.10
Offshore circalittoral mud	0.00	3	0.00	0.00	0.00	0.00	0.05	0.00	NA
Offshore circalittoral sand	0.00	5	0.00	0.00	0.00	0.00	0.01	0.00	NA
Offshore circalittoral coarse sediment	0.00	3	0.00	0.00	0.00	0.00	0.00	0.00	NA
Offshore circalittoral rock and biogenic reef	0.00	4	0.00	0.00	0.00	0.00	0.00	0.00	NA

Figure 3

Figure 3. Time series of (a) mean fishing intensity (surface abrasion), (b) proportion of the surface area of the seafloor fished, (c) aggregation of fishing (proportion of the surface area with 90% of the fishing effort) by habitat. Results represent vessels over 15m (2009-2011) and vessels over 12m (2012-2018).

Figure 4

Figure 4. Cumulative proportion of the swept area, landings and value. Grid cells were sorted from highest to lowest fishing intensity and include non-fished cells. The results are for all mobile bottom-contacting gears based on averaged fishing data per c-square from 2013-2018.

Core fishing grounds

Core fishing grounds are defined as the c-squares with the 90% highest value of landings in the VMS data. Figure 5 shows the number of years c-squares are within the 90% highest value by métier. Only two métiers are used in the Bothnian subregion: otter trawls for cod and plaice (OT_DMF) and for small pelagic fish (OT_SPF). If fishing in a métier occurs in the same c-square every year with high value of landings, the rightmost bar in Figure 5 will be high, meaning that the c-square is within the 90% highest value of landings every year during the period 2013-2018. If a c-square is only within the 90% highest value in one year, it will end up in the bar at the left. Figure 6 shows the percentage area overlap between the 90% highest value per year and the reference fishing ground. Both figures highlight that the fisheries for small pelagic fish (OT_SPF) has the highest variation in space.

Figure 7 illustrates the relationship between area fished in percent and the cumulated value of landings, sorted from the c-squares with highest value fisheries. The curves are generally starting steeply, illustrating the concentration of the fisheries at fishing grounds and the curves are ending horizontally, illustrating the peripheral fisheries going on outside the main fishing grounds.

Figure 8 shows the area associated with each 10-percentile interval for each métier using averages of SAR (left column) and landings value (euro, right column) for the period 2013-2018.

Figure 5

Figure 5. Number of years c-squares are within the 90% highest value by métier, presented as a % relative to the total number of c-squares (n) that are within the 90% highest value by métier across all years. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 6

Figure 6. Percentage area overlap between the 90% highest value per year and the reference core fishing ground. For métiers that are included in Figure 5 and missing in Figure 6, no reference core ground could be established and/or métiers were not used in the area in some years.

Figure 7

Figure 7. Percent area fished vs. landings value (euro) by métier, coloured by year. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 8

Figure 8. The area associated with each 10-percentile interval for each métier using averages of SAR (left column) and landings value (euro, right column) for the period 2013-2018. The lightest blue c-squares represent the lowest 10% of total SAR / value of landings. The brown c-squares represent the highest 10% of total SAR / value of landings.

Fishing by métier

Intensity, weight and value of landings are estimated for the grid cells that were fished by one MBCG métier, ignoring cells fished by other métiers (Table 3).

Only otter trawls for cod and plaice and small demersal fished have been used in the Bothnian subregion.

Table 3

Table 3. Overview of area fished (sum of swept area), landings and value for the different metiers. Area fished in 1000 km², weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Area swept (1000 km2)	0	0	0.47	0	0.65	0	0	0	0	0
Landings (1000 tonnes)	0	0	0.67	0	1.92	0	0	0	0	0
Value (10^6 euro)	0	0	2.68	0	0.85	0	0	0	0	0
Landings (1000 tonnes)/Area swept (1000 km2)	NaN	NaN	1.44	NaN	2.95	NaN	NaN	NaN	NaN	NaN
Value (10^6 euro)/Area swept (1000 km2)	NaN	NaN	5.73	NaN	1.31	NaN	NaN	NaN	NaN	NaN

Impact

The impact of mobile bottom-contacting fishing from the PD method shows areas of low fishing impact in the western part of the Bothnian subregion (Figure 9, left). High impact from the L1 method covers the same area (Figure 9, right), but indicates a higher impact.

The impact scores are constant and low over time (Figure 10, left panel). Impact does not vary much between habitats (Figure 9 shows the four most extensive habitat types). All habitat types (100%) have a PD impact score <0.2, whereas more than 95% of each habitat type has an L1 impact score <0.2.

Table 4 shows impact per métier relative to weight and value of landings. In this analysis, the different métiers are assessed for the grid cells that were fished by one MBCG métier, ignoring cells fished by other métiers. As such this estimates the maximum impact compared to the untrawled situation and the impact estimated assuming all other métiers to have impacted the habitat will be less than this. Only otter trawls for cod and plaice and small demersal fished have been used in the Bothnian subregion (Table 3).

Impact by all métiers are low for each habitat type (Figure 11).

Figure 9

Figure 9. Impact of mobile bottom-contacting gears averaged for the 2013-2018 six-year cycle for the PD and L1 method.

Figure 10

Figure 10. The mean impact of mobile bottom-contacting gears in all combined MSFD habitats and the four most extensive habitat types between 2009 and 2018 (left). The proportion of the fished area with an impact of less than 0.2 (right)

Table 4

Table 4. Overview of impact per metier relative to weight and value of landings estimated for the grid cells fished (SAR >0) with these métiers only. Weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Landings (1000 tonnes)/PD impact	NA	NA	0.809	NA	3.340	NA	NA	NA	NA	NA
Value (10^6 euro)/PD impact	NA	NA	3.219	NA	1.484	NA	NA	NA	NA	NA
Landings (1000 tonnes)/L1 impact	NA	NA	0.021	NA	0.063	NA	NA	NA	NA	NA
Value (10^6 euro)/L1 impact	NA	NA	0.082	NA	0.028	NA	NA	NA	NA	NA

Figure 11

Figure 11. PD impact (upper panel) and L1 impact (lower panel) of selected gear groupings on the most extensive MSFD habitat types. Impact is estimated in isolation of the other gear groupings. Note the different scales on the Y-axis.

Management scenarios

The figures and tables below show one implementation of multi-purpose habitat management through reductions in effort and spatial closures for the four most extensive MSFD habitat types. They show the changes in average impact (PD, L1), unfished area and fisheries values of landings based on a static assessment of effort removal.

The analysis is based on the progressive removal of 5 to 99% of all MBCG fishing effort, starting from the c-squares with the lowest effort (corrected for the areal extent of the MSFD habitat within each c-square). Blue dots show the current situation and are used as reference. The % of unfished area in the reference is only based on grid cells that are unfished. Average PD and L1 impacts are a weighted average and consider the areal extent of each MSFD habitat type within a grid cell.

Note that the fraction of grid cells above/below a certain impact threshold initially remains the same (not shown) as the removal of effort starts from the c-squares with the lowest effort that typically have low impact.

MSFD habitat - 1

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.01	90.13	100.00	100.00
5	0.01	96.04	94.93	94.77
10	0.01	97.24	89.46	89.88
15	0.01	97.89	82.03	85.10
20	0.01	98.22	76.98	81.71
30	0.01	98.79	64.30	72.29
40	0.01	99.19	50.77	62.03
60	0.00	99.51	30.56	46.82
80	0.00	99.80	17.90	23.54
99	0.00	100.00	3.41	6.02

MSFD habitat - 2

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Area unfished (%)	Value (%)	Weight (%)
0	95.19	100.00	100.00
5	97.74	97.59	94.75
10	98.62	93.52	87.52
15	99.09	90.95	82.81
20	99.26	85.79	78.26
30	99.49	75.11	68.77
40	99.61	61.09	60.42
60	99.82	42.75	41.86
80	99.93	20.19	21.51
99	100.00	7.40	2.47

MSFD habitat - 3

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.01	96.40	100.00	100.00
5	0.01	98.23	95.52	95.36
10	0.01	98.44	91.43	91.56
15	0.01	98.65	85.10	85.74
20	0.01	98.88	79.23	80.02
30	0.01	99.18	71.07	71.40
40	0.01	99.31	61.16	61.13
60	0.00	99.77	41.76	41.94
80	0.00	99.91	18.62	19.10
99	0.00	100.00	10.15	10.47

MSFD habitat - 4

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.02	90.32	100.00	100.00
5	0.01	95.48	97.75	94.29
10	0.01	96.64	95.79	88.61
15	0.01	97.32	93.24	84.62
20	0.01	97.71	91.73	78.14
30	0.01	98.16	86.70	64.74
40	0.01	98.92	80.99	59.58
60	0.00	99.58	68.35	40.01
80	0.00	99.83	46.81	17.19
99	0.00	100.00	30.18	10.55

Overview all MSFD habitats

Fishing effort consequences, as a % relative to total swept area, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Circalittoral mud or Circalittoral sand	28.12	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mixed sediment	55.99	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mixed sediment	4.86	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mud	3.22	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral sand	7.33	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral coarse sediment	3.25	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud or Infralittoral sand	0.47	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral sand	0.83	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral coarse sediment	0.52	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral rock and biogenic reef	1.91	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud	0.09	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral mud or Offshore circalittoral sand	0.01	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	10.8
Infralittoral rock and biogenic reef	1.33	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral mixed sediment	0.07	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral mud	0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral sand	0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral coarse sediment	0	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral rock and biogenic reef	0	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Fishing value consequences, as a % relative to total value, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Circalittoral mud or Circalittoral sand	28.12	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mixed sediment	55.99	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mixed sediment	4.86	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mud	3.22	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral sand	7.33	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral coarse sediment	3.25	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud or Infralittoral sand	0.47	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral sand	0.83	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral coarse sediment	0.52	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral rock and biogenic reef	1.91	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud	0.09	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral mud or Offshore circalittoral sand	0.01	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	4.2
Infralittoral rock and biogenic reef	1.33	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral mixed sediment	0.07	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral mud	0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral sand	0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral coarse sediment	0	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral rock and biogenic reef	0	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Fishing weight consequences, as a % relative to total weight, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Circalittoral mud or Circalittoral sand	28.12	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mixed sediment	55.99	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mixed sediment	4.86	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mud	3.22	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral sand	7.33	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral coarse sediment	3.25	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud or Infralittoral sand	0.47	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral sand	0.83	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral coarse sediment	0.52	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral rock and biogenic reef	1.91	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud	0.09	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral mud or Offshore circalittoral sand	0.01	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	7.1
Infralittoral rock and biogenic reef	1.33	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral mixed sediment	0.07	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral mud	0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral sand	0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral coarse sediment	0	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral rock and biogenic reef	0	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Gulf of Finland

Summary

The Gulf of Finland subdivision shows negligible amounts of fishing (Table 1, Figure 1).

Table 1

Table 1. Pressure and impact indicators for 2013-2018
Indicators	0 to 200 m	200 to 800 m	more than 800 m
Average intensity (I-1)	0.00	NA	NA
Proportion of area in fished cells (I-2)	0.01	NA	NA
Proportion of area fished per year (I-3)	0.00	NA	NA
Smallest prop. of area in fished cells with 90% of fishing effort (I-4)	0.01	NA	NA
Proportion of area in unfished cells (I-5)	0.99	NA	NA
Average PD impact (I-6)	0.00	NA	NA
Average L1 impact (I-6)	0.00	NA	NA
Proportion of area with PD impact < 0.2 (I-7)	1.00	NA	NA
Proportion of area with L1 impact < 0.2 (I-7)	1.00	NA	NA

Figure 1

Figure 1 Geographic distribution of surface abrasion, seabed sensitivity (community longevity) and total value and weight from mobile bottom-contacting gear. The maps of surface abrasion, value and weight show the average per year for 2013-2018

Pressure

The Gulf of Finland subdivision shows negligible amounts of fishing.

Figure 2

Figure 2 Surface abrasion, Swept Area Ratio, by mobile bottom-contacting gears (year-1), averaged for the 2013-2018 six-year cycle

Table 2

Table 2 Overview of pressure indicators of all mobile bottom-contacting gears per broad-scale habitat averaged for 2013-2018. I refers to the indicators in Table 1.
MSFD broad habitat type	Extent of habitat (1000 km²)	Number of grid cells	Landings 1000 tonnes	Prop. of area in fished grid cells (I-2)	Smallest prop. of area with 90% of fishing effort (I-4)
Circalittoral mud	3.08	786	0.01	0.02	0.01
Circalittoral mixed sediment	5.97	1317	0.00	0.01	0.00
Infralittoral rock and biogenic reef	0.70	579	0.00	0.01	0.00
Circalittoral mud or Circalittoral sand	6.27	1160	0.00	0.00	0.00
Infralittoral mixed sediment	0.95	786	0.00	0.00	0.00
Circalittoral rock and biogenic reef	1.10	816	0.00	0.00	0.00
Circalittoral coarse sediment	1.26	559	0.00	0.00	NA
Circalittoral sand	2.09	611	0.00	0.00	NA
Infralittoral coarse sediment	0.26	281	0.00	0.00	NA
Infralittoral mud	0.10	221	0.00	0.00	NA
Infralittoral mud or Infralittoral sand	0.61	494	0.00	0.00	NA
Infralittoral sand	0.73	361	0.00	0.00	NA
Offshore circalittoral coarse sediment	0.14	71	0.00	0.00	NA
Offshore circalittoral mixed sediment	0.88	271	0.00	0.00	NA
Offshore circalittoral mud	3.05	373	0.00	0.00	NA
Offshore circalittoral mud or Offshore circalittoral sand	0.92	187	0.00	0.00	NA
Offshore circalittoral rock and biogenic reef	0.06	63	0.00	0.00	NA
Offshore circalittoral sand	0.36	115	0.00	0.00	NA
Unknown	0.18	100	0.00	0.00	NA

Figure 3

Figure 3. Time series of (a) mean fishing intensity (surface abrasion), (b) proportion of the surface area of the seafloor fished, (c) aggregation of fishing (proportion of the surface area with 90% of the fishing effort) by habitat. Results represent vessels over 15m (2009-2011) and vessels over 12m (2012-2018).

Figure 4

Figure 4. Cumulative proportion of the swept area, landings and value. Grid cells were sorted from highest to lowest fishing intensity and include non-fished cells. The results are for all mobile bottom-contacting gears based on averaged fishing data per c-square from 2013-2018.

Core fishing grounds

The Gulf of Finland subdivision shows negligible amounts of fishing.

Figure 5

Figure 5. Number of years c-squares are within the 90% highest value by métier, presented as a % relative to the total number of c-squares (n) that are within the 90% highest value by métier across all years. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 6

Figure 6. Percentage area overlap between the 90% highest value per year and the reference core fishing ground. For métiers that are included in Figure 5 and missing in Figure 6, no reference core ground could be established and/or métiers were not used in the area in some years.

Figure 7

Figure 7. Percent area fished vs. landings value (euro) by métier, coloured by year. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 8

Figure 8. The area associated with each 10-percentile interval for each métier using averages of SAR (left column) and landings value (euro, right column) for the period 2013-2018. The lightest blue c-squares represent the lowest 10% of total SAR / value of landings. The brown c-squares represent the highest 10% of total SAR / value of landings.

Fishing by métier

The Gulf of Finland subdivision shows negligible amounts of fishing.

Table 3

Table 3. Overview of area fished (sum of swept area), landings and value for the different metiers. Area fished in 1000 km², weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Area swept (1000 km2)	0	0	0	0	<0.005	0	0	0	0	0
Landings (1000 tonnes)	0	0	0	0	0.01	0	0	0	0	0
Value (10^6 euro)	0	0	0	0	<0.005	0	0	0	0	0
Landings (1000 tonnes)/Area swept (1000 km2)	NaN	NaN	NaN	NaN	11.15	NaN	NaN	NaN	NaN	NaN
Value (10^6 euro)/Area swept (1000 km2)	NaN	NaN	NaN	NaN	2.23	NaN	NaN	NaN	NaN	NaN

Impact

The Gulf of Finland subdivision shows negligible amounts of fishing and no impact.

Figure 9

Figure 9. Impact of mobile bottom-contacting gears averaged for the 2013-2018 six-year cycle for the PD and L1 method.

Figure 10

Figure 10. The mean impact of mobile bottom-contacting gears in all combined MSFD habitats and the four most extensive habitat types between 2009 and 2018 (left). The proportion of the fished area with an impact of less than 0.2 (right)

Table 4

Table 4. Overview of impact per metier relative to weight and value of landings estimated for the grid cells fished (SAR >0) with these métiers only. Weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Landings (1000 tonnes)/PD impact	NA	NA	NA	NA	2.080	NA	NA	NA	NA	NA
Value (10^6 euro)/PD impact	NA	NA	NA	NA	0.417	NA	NA	NA	NA	NA
Landings (1000 tonnes)/L1 impact	NA	NA	NA	NA	1.771	NA	NA	NA	NA	NA
Value (10^6 euro)/L1 impact	NA	NA	NA	NA	0.355	NA	NA	NA	NA	NA

Figure 11

Figure 11. PD impact (upper panel) and L1 impact (lower panel) of selected gear groupings on the most extensive MSFD habitat types. Impact is estimated in isolation of the other gear groupings. Note the different scales on the Y-axis.

Management scenarios

The Gulf of Finland subdivision shows negligible amounts of fishing, and thus output is not available for this region.

MSFD habitat - 1

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Area unfished (%)	Value (%)	Weight (%)
0	98.11	100.00	100.00
5	98.77	94.14	93.97
10	98.77	94.14	93.97
15	99.18	89.11	89.17
20	99.54	85.38	85.61
30	100.00	70.33	69.76
40	100.00	70.33	69.76
60	100.00	70.33	69.76
80	100.00	70.33	69.76
99	100.00	70.33	69.76

MSFD habitat - 2

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Area unfished (%)	Value (%)	Weight (%)
0	99.12	100.00	100.00
5	99.25	97.28	97.42
10	99.25	97.28	97.42
15	99.25	97.28	97.42
20	99.42	84.05	83.52
30	99.60	76.53	76.08
40	99.60	76.53	76.08
60	99.85	44.99	43.90
80	100.00	25.03	24.45
99	100.00	25.03	24.45

MSFD habitat - 3

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Area unfished (%)	Value (%)	Weight (%)
0	98.63	100.00	100.00
5	99.19	100.00	100.00
10	99.19	100.00	100.00
15	99.19	100.00	100.00
20	99.19	100.00	100.00
30	100.00	84.33	84.15
40	100.00	84.33	84.15
60	100.00	84.33	84.15
80	100.00	84.33	84.15
99	100.00	84.33	84.15

MSFD habitat - 4

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Area unfished (%)	Value (%)	Weight (%)
0	99.95	100	100
5	100.00	100	100
10	100.00	100	100
15	100.00	100	100
20	100.00	100	100
30	100.00	100	100
40	100.00	100	100
60	100.00	100	100
80	100.00	100	100
99	100.00	100	100

Overview all MSFD habitats

Fishing effort consequences, as a % relative to total swept area, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Circalittoral mud	3.08	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mixed sediment	5.97	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral rock and biogenic reef	0.7	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mud or Circalittoral sand	6.27	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mixed sediment	0.95	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral rock and biogenic reef	1.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral coarse sediment	1.26	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral sand	2.09	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral coarse sediment	0.26	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral mud	0.1	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral mud or Infralittoral sand	0.61	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral sand	0.73	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral coarse sediment	0.14	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mixed sediment	0.88	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mud	3.05	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mud or Offshore circalittoral sand	0.92	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral rock and biogenic reef	0.06	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral sand	0.36	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Unknown	0.18	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Fishing value consequences, as a % relative to total value, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Circalittoral mud	3.08	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mixed sediment	5.97	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral rock and biogenic reef	0.7	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mud or Circalittoral sand	6.27	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mixed sediment	0.95	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral rock and biogenic reef	1.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral coarse sediment	1.26	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral sand	2.09	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral coarse sediment	0.26	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral mud	0.1	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral mud or Infralittoral sand	0.61	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral sand	0.73	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral coarse sediment	0.14	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mixed sediment	0.88	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mud	3.05	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mud or Offshore circalittoral sand	0.92	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral rock and biogenic reef	0.06	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral sand	0.36	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Unknown	0.18	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Fishing weight consequences, as a % relative to total weight, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Circalittoral mud	3.08	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mixed sediment	5.97	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral rock and biogenic reef	0.7	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mud or Circalittoral sand	6.27	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mixed sediment	0.95	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral rock and biogenic reef	1.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral coarse sediment	1.26	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral sand	2.09	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral coarse sediment	0.26	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral mud	0.1	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral mud or Infralittoral sand	0.61	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral sand	0.73	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral coarse sediment	0.14	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mixed sediment	0.88	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mud	3.05	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mud or Offshore circalittoral sand	0.92	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral rock and biogenic reef	0.06	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral sand	0.36	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Unknown	0.18	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Gulf of Riga

Summary

The Gulf of Riga subdivision shows negligible amounts of fishing (Table 1, Figure 1).

Table 1

Table 1. Pressure and impact indicators for 2013-2018
Indicators	0 to 200 m	200 to 800 m	more than 800 m
Average intensity (I-1)	0	NA	NA
Proportion of area in fished cells (I-2)	0	NA	NA
Proportion of area fished per year (I-3)	0	NA	NA
Smallest prop. of area in fished cells with 90% of fishing effort (I-4)	0	NA	NA
Proportion of area in unfished cells (I-5)	1	NA	NA
Average PD impact (I-6)	0	NA	NA
Average L1 impact (I-6)	0	NA	NA
Proportion of area with PD impact < 0.2 (I-7)	1	NA	NA
Proportion of area with L1 impact < 0.2 (I-7)	1	NA	NA

Figure 1

Figure 1 Geographic distribution of surface abrasion, seabed sensitivity (community longevity) and total value and weight from mobile bottom-contacting gear. The maps of surface abrasion, value and weight show the average per year for 2013-2018

Pressure

The Gulf of Riga subdivision shows negligible amounts of fishing.

Figure 2

Figure 2 Surface abrasion, Swept Area Ratio, by mobile bottom-contacting gears (year-1), averaged for the 2013-2018 six-year cycle

Table 2

Table 2 Overview of pressure indicators of all mobile bottom-contacting gears per broad-scale habitat averaged for 2013-2018. I refers to the indicators in Table 1.
MSFD broad habitat type	Extent of habitat (1000 km²)	Number of grid cells	Landings 1000 tonnes	Prop. of area in fished grid cells (I-2)	Smallest prop. of area with 90% of fishing effort (I-4)
Infralittoral mixed sediment	1.44	223	0.00	0.01	0.00
Circalittoral mixed sediment	5.46	539	0.00	0.00	0.00
Infralittoral mud or Infralittoral sand	0.83	120	0.05	0.04	0.02
Circalittoral coarse sediment	0.48	119	0.00	0.00	NA
Circalittoral mud	5.17	504	0.00	0.00	NA
Circalittoral mud or Circalittoral sand	1.99	291	0.00	0.00	NA
Circalittoral rock and biogenic reef	0.05	30	0.00	0.00	NA
Circalittoral sand	1.34	284	0.00	0.00	NA
Infralittoral coarse sediment	0.57	145	0.00	0.00	NA
Infralittoral mud	0.01	8	0.00	0.00	NA
Infralittoral rock and biogenic reef	0.04	16	0.00	0.00	NA
Infralittoral sand	0.71	149	0.00	0.00	NA
Offshore circalittoral mixed sediment	0.00	1	0.00	0.00	NA
Offshore circalittoral mud	0.01	2	0.00	0.00	NA

Figure 3

Figure 3. Time series of (a) mean fishing intensity (surface abrasion), (b) proportion of the surface area of the seafloor fished, (c) aggregation of fishing (proportion of the surface area with 90% of the fishing effort) by habitat. Results represent vessels over 15m (2009-2011) and vessels over 12m (2012-2018).

Figure 4

Figure 4. Cumulative proportion of the swept area, landings and value. Grid cells were sorted from highest to lowest fishing intensity and include non-fished cells. The results are for all mobile bottom-contacting gears based on averaged fishing data per c-square from 2013-2018.

Core fishing grounds

The Gulf of Riga subdivision shows negligible amounts of fishing.

Figure 5

Figure 5. Number of years c-squares are within the 90% highest value by métier, presented as a % relative to the total number of c-squares (n) that are within the 90% highest value by métier across all years. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 6

Figure 6. Percentage area overlap between the 90% highest value per year and the reference core fishing ground. For métiers that are included in Figure 5 and missing in Figure 6, no reference core ground could be established and/or métiers were not used in the area in some years.

Figure 7

Figure 7. Percent area fished vs. landings value (euro) by métier, coloured by year. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 8

Figure 8. The area associated with each 10-percentile interval for each métier using averages of SAR (left column) and landings value (euro, right column) for the period 2013-2018. The lightest blue c-squares represent the lowest 10% of total SAR / value of landings. The brown c-squares represent the highest 10% of total SAR / value of landings.

Fishing by métier

The Gulf of Riga subdivision shows negligible amounts of fishing.

Table 3

Table 3. Overview of area fished (sum of swept area), landings and value for the different metiers. Area fished in 1000 km², weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Area swept (1000 km2)	<0.005	0	<0.005	0	0	0	0	0	0	0
Landings (1000 tonnes)	0.05	0	<0.005	0	0	0	0	0	0	0
Value (10^6 euro)	<0.005	0	<0.005	0	0	0	0	0	0	0
Landings (1000 tonnes)/Area swept (1000 km2)	2133.71	NaN	0.01	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Value (10^6 euro)/Area swept (1000 km2)	85.35	NaN	<0.005	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Impact

The Gulf of Riga subdivision shows negligible amounts of fishing, and negligible impacts.

Figure 9

Figure 9. Impact of mobile bottom-contacting gears averaged for the 2013-2018 six-year cycle for the PD and L1 method.

Figure 10

Figure 10. The mean impact of mobile bottom-contacting gears in all combined MSFD habitats and the four most extensive habitat types between 2009 and 2018 (left). The proportion of the fished area with an impact of less than 0.2 (right)

Table 4

Table 4. Overview of impact per metier relative to weight and value of landings estimated for the grid cells fished (SAR >0) with these métiers only. Weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Landings (1000 tonnes)/PD impact	34.438	NA	0.003	NA	NA	NA	NA	NA	NA	NA
Value (10^6 euro)/PD impact	1.378	NA	0.001	NA	NA	NA	NA	NA	NA	NA
Landings (1000 tonnes)/L1 impact	39.745	NA	0.002	NA	NA	NA	NA	NA	NA	NA
Value (10^6 euro)/L1 impact	1.590	NA	0.001	NA	NA	NA	NA	NA	NA	NA

Figure 11

Figure 11. PD impact (upper panel) and L1 impact (lower panel) of selected gear groupings on the most extensive MSFD habitat types. Impact is estimated in isolation of the other gear groupings. Note the different scales on the Y-axis.

Management scenarios

The Gulf of Riga subdivision shows negligible amounts of fishing, and thus output is not available for this region.

MSFD habitat - 1

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Area unfished (%)	Value (%)	Weight (%)
0	99.34	100	100
5	100.00	100	100
10	100.00	100	100
15	100.00	100	100
20	100.00	100	100
30	100.00	100	100
40	100.00	100	100
60	100.00	100	100
80	100.00	100	100
99	100.00	100	100

MSFD habitat - 2

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Area unfished (%)	Value (%)	Weight (%)
0	99.87	100	100
5	100.00	100	100
10	100.00	100	100
15	100.00	100	100
20	100.00	100	100
30	100.00	100	100
40	100.00	100	100
60	100.00	100	100
80	100.00	100	100
99	100.00	100	100

MSFD habitat - 3

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Area unfished (%)	Value (%)	Weight (%)
0	96.11	100.00	100.00
5	98.05	100.00	100.00
10	98.05	100.00	100.00
15	98.05	100.00	100.00
20	98.05	100.00	100.00
30	98.05	100.00	100.00
40	98.05	100.00	100.00
60	100.00	49.64	49.64
80	100.00	49.64	49.64
99	100.00	49.64	49.64

MSFD habitat - 4

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0	0	100	NA	NA
5	NA	NA	NA	NA	NA
10	NA	NA	NA	NA	NA
15	NA	NA	NA	NA	NA
20	NA	NA	NA	NA	NA
30	NA	NA	NA	NA	NA
40	NA	NA	NA	NA	NA
60	NA	NA	NA	NA	NA
80	NA	NA	NA	NA	NA
99	NA	NA	NA	NA	NA

Overview all MSFD habitats

Fishing effort consequences, as a % relative to total swept area, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Infralittoral mixed sediment	1.44	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mixed sediment	5.46	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud or Infralittoral sand	0.83	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral coarse sediment	0.48	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral mud	5.17	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral mud or Circalittoral sand	1.99	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral rock and biogenic reef	0.05	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral sand	1.34	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral coarse sediment	0.57	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral mud	0.01	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral rock and biogenic reef	0.04	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral sand	0.71	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mixed sediment	0	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mud	0.01	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Fishing value consequences, as a % relative to total value, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Infralittoral mixed sediment	1.44	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mixed sediment	5.46	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud or Infralittoral sand	0.83	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral coarse sediment	0.48	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral mud	5.17	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral mud or Circalittoral sand	1.99	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral rock and biogenic reef	0.05	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral sand	1.34	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral coarse sediment	0.57	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral mud	0.01	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral rock and biogenic reef	0.04	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral sand	0.71	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mixed sediment	0	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mud	0.01	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Fishing weight consequences, as a % relative to total weight, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Infralittoral mixed sediment	1.44	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral mixed sediment	5.46	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud or Infralittoral sand	0.83	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Circalittoral coarse sediment	0.48	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral mud	5.17	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral mud or Circalittoral sand	1.99	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral rock and biogenic reef	0.05	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Circalittoral sand	1.34	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral coarse sediment	0.57	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral mud	0.01	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral rock and biogenic reef	0.04	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Infralittoral sand	0.71	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mixed sediment	0	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN
Offshore circalittoral mud	0.01	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Baltic Proper

Summary

The physical disturbance pressures from mobile bottom-contacting fishing gears is spatially constrained in the Baltic Proper subdivision with 26% of the grid cells (I-2), and 10% of the surface area (I-3), in the depth zone 0-200m, being fished on average per year for the period 2013-2018 (Table 1). Fishing is very aggregated with 90% of the pressure occurring in 7% of grid cells (I-4).

The PD method shows an average decline in community biomass of 0% relative to carrying capacity across c-squares (I-6). All c-squares (100% (I-7)), have an impact score less than 20%. The L1 method shows an average impact of 0.09 across c-squares (I-6). The majority of c-squares, 88% (I-7), have impact scores less than 20% (I-7).

Maps of spatial distribution of intensity (surface abrasion), seafloor sensitivity and economic value and weight of fisheries landings are shown in Figure 1. Activity is mostly concentrated in the south area of the Baltic Proper (Figure 1).

Table 1

Table 1. Pressure and impact indicators for 2013-2018
Indicators	0 to 200 m	200 to 800 m	more than 800 m
Average intensity (I-1)	0.26	0	NA
Proportion of area in fished cells (I-2)	0.26	0	NA
Proportion of area fished per year (I-3)	0.10	0	NA
Smallest prop. of area in fished cells with 90% of fishing effort (I-4)	0.07	NA	NA
Proportion of area in unfished cells (I-5)	0.74	1	NA
Average PD impact (I-6)	0.00	0	NA
Average L1 impact (I-6)	0.09	0	NA
Proportion of area with PD impact < 0.2 (I-7)	1.00	1	NA
Proportion of area with L1 impact < 0.2 (I-7)	0.88	1	NA

Figure 1

Figure 1 Geographic distribution of surface abrasion, seabed sensitivity (community longevity) and total value and weight from mobile bottom-contacting gear. The maps of surface abrasion, value and weight show the average per year for 2013-2018

Pressure

The distribution of fishing intensity in the Baltic Proper subregion is mostly concentrated in the south area (Figure 2).

The proportion of area subject to fishing pressure differs between broad-scale habitats and is highest in circalittoral sand (49% of grid cells fished) and offshore circalittoral mud (40% of grid cells fished) (Table 2). The highest fishing intensity is found in the offshore circalittoral mud (1.02 yr-1) and the offshore circalittoral sand (1.98 yr-1) (Table 2).

Figure 3 shows the fishing intensity for the four largest MSDF broad-scale habitats. Total fishing intensity peaked in 2012, and has been very stable afterwards (Figure 3). This trend is predominantly driven by the offshore circalittoral mixed sediment and circalittoral mud or sand (Figure 3). The average trawling intensity is more variable over time than the proportion of area fished (Figure 3, compare left and middle panel). This shows that changes in intensity have not affected the spatial distribution of the footprint much.

Fishing pressure is highly aggregated, both at the regional level as well as at the level of the habitat (Figure 3, right panel). The smallest proportion of habitat with 90% of effort is less than 10%. The intensively fished areas represent the ‘core fishing grounds’. These grounds contribute most of the landings and value (Figure 4). More than 80% of the fishing effort (swept area), landings and value, occur in 10% of the surface area of the Baltic Proper (Figure 4).

Figure 2

Figure 2 Surface abrasion, Swept Area Ratio, by mobile bottom-contacting gears (year-1), averaged for the 2013-2018 six-year cycle

Table 2

Table 2 Overview of pressure indicators of all mobile bottom-contacting gears per broad-scale habitat averaged for 2013-2018. I refers to the indicators in Table 1.
MSFD broad habitat type	Extent of habitat (1000 km²)	Number of grid cells	Landings 1000 tonnes	Value 10⁶ euro	Swept area 1000 km²	Average intensity (I-1)	Prop. of area in fished grid cells (I-2)	Prop. of area fished per year (I-3)	Smallest prop. of area with 90% of fishing effort (I-4)
Offshore circalittoral mixed sediment	15.31	2113	3.94	4.03	12.21	0.80	0.33	0.21	0.08
Offshore circalittoral mud	8.44	1272	2.76	2.95	8.59	1.02	0.40	0.30	0.11
Circalittoral sand	11.72	1871	2.10	1.23	4.12	0.35	0.49	0.17	0.08
Circalittoral mud	7.50	1622	1.77	1.36	3.66	0.49	0.34	0.20	0.06
Circalittoral mud or Circalittoral sand	16.27	2081	1.58	0.59	2.84	0.17	0.32	0.13	0.07
Offshore circalittoral mud or Offshore circalittoral sand	31.52	2728	0.95	0.75	2.02	0.06	0.21	0.05	0.05
Offshore circalittoral sand	0.70	200	0.43	0.49	1.39	1.98	0.61	0.41	0.16
Circalittoral mixed sediment	28.95	3576	2.32	0.66	1.11	0.04	0.17	0.02	0.03
Circalittoral coarse sediment	5.85	1390	0.24	0.06	0.16	0.03	0.22	0.02	0.06
Infralittoral sand	2.31	728	0.05	0.03	0.15	0.06	0.21	0.06	0.04
Circalittoral rock and biogenic reef	3.73	1065	0.03	0.01	0.03	0.01	0.07	0.01	0.02
Infralittoral coarse sediment	2.20	759	0.02	0.01	0.02	0.01	0.08	0.01	0.02
Infralittoral mud or Infralittoral sand	1.96	271	0.00	0.00	0.01	0.01	0.02	0.01	0.02
Infralittoral mixed sediment	5.43	1204	0.01	0.00	0.00	0.00	0.02	0.00	0.01
Infralittoral rock and biogenic reef	1.36	617	0.00	0.00	0.00	0.00	0.02	0.00	0.01
Infralittoral mud	0.18	277	0.00	0.00	0.00	0.00	0.04	0.00	0.01
Offshore circalittoral coarse sediment	0.56	421	0.00	0.00	0.00	0.00	0.14	0.00	0.03
Offshore circalittoral rock and biogenic reef	0.12	161	0.00	0.00	0.00	0.00	0.03	0.00	0.02

Figure 3

Figure 3. Time series of (a) mean fishing intensity (surface abrasion), (b) proportion of the surface area of the seafloor fished, (c) aggregation of fishing (proportion of the surface area with 90% of the fishing effort) by habitat. Results represent vessels over 15m (2009-2011) and vessels over 12m (2012-2018).

Figure 4

Figure 4. Cumulative proportion of the swept area, landings and value. Grid cells were sorted from highest to lowest fishing intensity and include non-fished cells. The results are for all mobile bottom-contacting gears based on averaged fishing data per c-square from 2013-2018.

Core fishing grounds

Core fishing grounds are defined as the c-squares with the 90% highest value of landings in the VMS data. Figure 5 shows the number of years c-squares are within the 90% highest value by métier. Only two métiers are used in the Baltic Proper subregion: otter trawls for cod and plaice (OT_DMF) and for small pelagic fish (OT_SPF). If fishing in a métier occurs in the same c-square every year with high value of landings, the rightmost bar in Figure 5 will be high, meaning that the c-square is within the 90% highest value of landings every year during the period 2013-2018. If a c-square is only within the 90% highest value in one year, it will end up in the bar at the left. Figure 6 shows the percentage area overlap between the 90% highest value per year and the reference fishing ground. Both figures highlight that the fisheries for small pelagic fish (OT_SPF) has the highest variation in space.

Figure 7 illustrates the relationship between area fished in percent and the cumulated value of landings, sorted from the c-squares with highest value fisheries. The curves are generally starting steeply, illustrating the concentration of the fisheries at fishing grounds and the curves are ending horizontally, illustrating the peripheral fisheries going on outside the main fishing grounds.

Figure 8 shows the area associated with each 10-percentile interval for each métier using averages of SAR (left column) and landings value (euro, right column) for the period 2013-2018.

Figure 5

Figure 5. Number of years c-squares are within the 90% highest value by métier, presented as a % relative to the total number of c-squares (n) that are within the 90% highest value by métier across all years. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 6

Figure 6. Percentage area overlap between the 90% highest value per year and the reference core fishing ground. For métiers that are included in Figure 5 and missing in Figure 6, no reference core ground could be established and/or métiers were not used in the area in some years.

Figure 7

Figure 7. Percent area fished vs. landings value (euro) by métier, coloured by year. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 8

Figure 8. The area associated with each 10-percentile interval for each métier using averages of SAR (left column) and landings value (euro, right column) for the period 2013-2018. The lightest blue c-squares represent the lowest 10% of total SAR / value of landings. The brown c-squares represent the highest 10% of total SAR / value of landings.

Fishing by métier

Intensity, weight and value of landings are estimated for the grid cells that were fished by one MBCG métier, ignoring cells fished by other métiers (Table 3).

Otter trawls for crustaceans (OT_CRU) have the highest landings and value per area swept (Table 3) but note the very small area fished.

Table 3

Table 3. Overview of area fished (sum of swept area), landings and value for the different metiers. Area fished in 1000 km², weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Area swept (1000 km2)	0	<0.005	35.20	0	1.14	0	0	0	0	0
Landings (1000 tonnes)	0	0.01	11.78	0	4.44	0	0	0	0	0
Value (10^6 euro)	0	<0.005	11.21	0	0.98	0	0	0	0	0
Landings (1000 tonnes)/Area swept (1000 km2)	NaN	6.93	0.33	NaN	3.91	NaN	NaN	NaN	NaN	NaN
Value (10^6 euro)/Area swept (1000 km2)	NaN	2.06	0.32	NaN	0.86	NaN	NaN	NaN	NaN	NaN

Impact

The impact of mobile bottom-contacting fishing from the PD method shows areas of low fishing impact in the southern part of the Baltic Proper subregion (Figure 9, left). High impact from the L1 method covers a slightly larger area, and includes the south-western part of the Baltic Proper (Figure 9, right).

The impact scores are constant and low over time (Figure 10, left panel). Impact does not vary much between habitats (Figure 9 shows the four most extensive habitat types). All habitat types (100%) have a PD impact score <0.2, whereas more than 75% of each habitat type has an L1 impact score <0.2.

Table 4 shows impact per métier relative to weight and value of landings. In this analysis, the different métiers are assessed for the grid cells that were fished by one MBCG métier, ignoring cells fished by other métiers. As such this estimates the maximum impact compared to the untrawled situation and the impact estimated assuming all other métiers to have impacted the habitat will be less than this. Otter trawls for crustaceans (OT_CRU) have the highest value per impact in the Baltic Proper subregion (Table 3).

Impact by all métiers are low for each habitat type (Figure 11).

Figure 9

Figure 9. Impact of mobile bottom-contacting gears averaged for the 2013-2018 six-year cycle for the PD and L1 method.

Figure 10

Figure 10. The mean impact of mobile bottom-contacting gears in all combined MSFD habitats and the four most extensive habitat types between 2009 and 2018 (left). The proportion of the fished area with an impact of less than 0.2 (right)

Table 4

Table 4. Overview of impact per metier relative to weight and value of landings estimated for the grid cells fished (SAR >0) with these métiers only. Weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Landings (1000 tonnes)/PD impact	NA	1.223	0.319	NA	4.730	NA	NA	NA	NA	NA
Value (10^6 euro)/PD impact	NA	0.363	0.303	NA	1.043	NA	NA	NA	NA	NA
Landings (1000 tonnes)/L1 impact	NA	1.806	0.017	NA	0.082	NA	NA	NA	NA	NA
Value (10^6 euro)/L1 impact	NA	0.536	0.016	NA	0.018	NA	NA	NA	NA	NA

Figure 11

Figure 11. PD impact (upper panel) and L1 impact (lower panel) of selected gear groupings on the most extensive MSFD habitat types. Impact is estimated in isolation of the other gear groupings. Note the different scales on the Y-axis.

Management scenarios

The figures and tables below show one implementation of multi-purpose habitat management through reductions in effort and spatial closures for the four most extensive MSFD habitat types. They show the changes in average impact (PD, L1), unfished area and fisheries values of landings based on a static assessment of effort removal.

The analysis is based on the progressive removal of 5 to 99% of all MBCG fishing effort, starting from the c-squares with the lowest effort (corrected for the areal extent of the MSFD habitat within each c-square). Blue dots show the current situation and are used as reference. The % of unfished area in the reference is only based on grid cells that are unfished. Average PD and L1 impacts are a weighted average and consider the areal extent of each MSFD habitat type within a grid cell.

Note that the fraction of grid cells above/below a certain impact threshold initially remains the same (not shown) as the removal of effort starts from the c-squares with the lowest effort that typically have low impact.

MSFD habitat - 1

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.01	0.20	66.73	100.00	100.00
5	0.01	0.17	81.72	94.49	91.81
10	0.01	0.16	84.10	89.33	86.68
15	0.01	0.14	86.16	84.15	81.48
20	0.01	0.12	87.61	79.24	76.69
30	0.01	0.10	90.10	68.69	66.33
40	0.01	0.08	92.32	59.16	56.98
60	0.01	0.05	95.55	39.15	37.86
80	0.00	0.02	98.15	19.39	18.84
99	0.00	0.00	100.00	1.38	1.28

MSFD habitat - 2

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.02	0.26	60.31	100.00	100.00
5	0.02	0.23	72.71	93.96	92.11
10	0.02	0.20	77.89	88.54	86.74
15	0.02	0.18	81.33	83.14	81.26
20	0.01	0.15	83.94	77.75	75.94
30	0.01	0.12	87.52	67.41	66.14
40	0.01	0.10	90.34	56.80	55.95
60	0.01	0.05	94.70	36.96	36.63
80	0.00	0.02	97.84	19.53	19.20
99	0.00	0.00	100.00	2.12	1.99

MSFD habitat - 3

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.01	0.17	50.79	100.00	100.00
5	0.01	0.15	77.24	95.69	94.27
10	0.01	0.13	82.29	91.67	90.08
15	0.01	0.11	85.90	86.98	83.62
20	0.00	0.10	88.27	82.26	77.11
30	0.00	0.07	92.08	71.08	61.21
40	0.00	0.05	94.84	62.28	48.55
60	0.00	0.02	97.98	45.48	27.73
80	0.00	0.01	99.41	26.27	15.74
99	0.00	0.00	100.00	8.84	5.39

MSFD habitat - 4

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.01	0.18	66.45	100.00	100.00
5	0.01	0.16	81.07	93.37	86.53
10	0.01	0.15	83.16	88.13	78.71
15	0.01	0.13	85.55	83.36	73.15
20	0.01	0.12	87.55	78.21	69.30
30	0.01	0.09	90.38	68.63	61.62
40	0.00	0.07	92.60	57.37	42.40
60	0.00	0.04	95.95	37.90	28.89
80	0.00	0.02	98.38	20.45	16.13
99	0.00	0.00	100.00	4.57	3.76

Overview all MSFD habitats

Fishing effort consequences, as a % relative to total swept area, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.4	0.5	0.6	0.7	0.8	0.9
Offshore circalittoral mixed sediment	15.31	0.0	0.0	0.0	<0.1	3.0	29.9
Offshore circalittoral mud	8.44	0.0	0.0	0.0	2.9	12.7	39.5
Circalittoral sand	11.72	0.0	0.0	0.4	1.7	7.6	24.4
Circalittoral mud	7.5	0.0	0.0	0.0	<0.1	4.1	29.7
Circalittoral mud or Circalittoral sand	16.27	0.0	0.0	0.0	<0.1	1.9	23.0
Offshore circalittoral mud or Offshore circalittoral sand	31.52	0.0	0.0	0.0	0.0	<0.1	2.9
Offshore circalittoral sand	0.7	<0.1	0.3	1.7	16.5	45.9	74.7
Circalittoral mixed sediment	28.95	0.0	0.0	0.0	0.0	0.0	1.9
Circalittoral coarse sediment	5.85	0.0	0.0	0.0	0.0	0.6	6.9
Infralittoral sand	2.31	0.0	0.0	0.0	0.0	<0.1	11.0
Circalittoral rock and biogenic reef	3.73	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral coarse sediment	2.2	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud or Infralittoral sand	1.96	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mixed sediment	5.43	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral rock and biogenic reef	1.36	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud	0.18	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral coarse sediment	0.56	0.0	0.0	0.0	0.0	0.0	28.2
Offshore circalittoral rock and biogenic reef	0.12	0.0	0.0	0.0	0.0	0.0	0.0

Fishing value consequences, as a % relative to total value, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.4	0.5	0.6	0.7	0.8	0.9
Offshore circalittoral mixed sediment	15.31	0.0	0.0	0.0	0.1	3.6	31.3
Offshore circalittoral mud	8.44	0.0	0.0	0.0	3.9	14.5	43.2
Circalittoral sand	11.72	0.0	<0.1	0.4	1.4	6.7	22.5
Circalittoral mud	7.5	0.0	<0.1	<0.1	0.3	5.9	31.4
Circalittoral mud or Circalittoral sand	16.27	0.0	0.0	0.0	0.5	4.9	31.4
Offshore circalittoral mud or Offshore circalittoral sand	31.52	0.0	0.0	<0.1	<0.1	0.3	7.4
Offshore circalittoral sand	0.7	<0.1	0.7	1.9	17.0	46.2	73.4
Circalittoral mixed sediment	28.95	0.0	0.0	0.0	0.0	0.0	2.2
Circalittoral coarse sediment	5.85	0.0	0.0	0.0	<0.1	1.0	8.8
Infralittoral sand	2.31	0.0	0.0	0.0	0.0	0.2	15.8
Circalittoral rock and biogenic reef	3.73	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral coarse sediment	2.2	0.0	0.0	0.0	0.0	0.3	0.3
Infralittoral mud or Infralittoral sand	1.96	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mixed sediment	5.43	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral rock and biogenic reef	1.36	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud	0.18	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral coarse sediment	0.56	0.0	0.0	0.0	0.0	0.0	79.7
Offshore circalittoral rock and biogenic reef	0.12	0.0	0.0	0.0	0.0	0.0	0.0

Fishing weight consequences, as a % relative to total weight, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.4	0.5	0.6	0.7	0.8	0.9
Offshore circalittoral mixed sediment	15.31	0.0	0.0	0.0	0.5	6.3	33.7
Offshore circalittoral mud	8.44	0.0	0.0	0.0	5.8	16.4	44.0
Circalittoral sand	11.72	0.0	<0.1	0.7	1.8	8.1	29.9
Circalittoral mud	7.5	0.0	<0.1	<0.1	0.7	12.9	38.4
Circalittoral mud or Circalittoral sand	16.27	0.0	0.0	0.0	0.8	7.2	33.4
Offshore circalittoral mud or Offshore circalittoral sand	31.52	0.0	0.0	0.2	0.2	1.8	28.1
Offshore circalittoral sand	0.7	0.2	1.8	3.0	18.4	47.5	74.4
Circalittoral mixed sediment	28.95	0.0	0.0	0.0	0.0	0.0	2.1
Circalittoral coarse sediment	5.85	0.0	0.0	0.0	<0.1	1.1	7.8
Infralittoral sand	2.31	0.0	0.0	0.0	0.0	0.4	22.8
Circalittoral rock and biogenic reef	3.73	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral coarse sediment	2.2	0.0	0.0	0.0	0.0	0.3	0.3
Infralittoral mud or Infralittoral sand	1.96	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mixed sediment	5.43	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral rock and biogenic reef	1.36	0.0	0.0	0.0	0.0	0.0	0.0
Infralittoral mud	0.18	0.0	0.0	0.0	0.0	0.0	0.0
Offshore circalittoral coarse sediment	0.56	0.0	0.0	0.0	0.0	0.0	75.9
Offshore circalittoral rock and biogenic reef	0.12	0.0	0.0	0.0	0.0	0.0	0.0

Arkona & Bornholm Basin

Summary

The physical disturbance pressures from mobile bottom-contacting fishing gears is relatively uniform across the Arkona and Bornholm Basin subdivision with 78% of the grid cells (I-2), and 42% of the surface area (I-3), in the depth zone 0-200m, being fished on average per year for the period 2013-2018 (Table 1). Fishing is not so aggregated with 90% of the pressure occurring in 31% of grid cells (I-4).

The PD method shows an average decline in community biomass of 2% relative to carrying capacity across c-squares (I-6). Virtually all c-squares (99% (I-7)), have an impact score less than 20%. The L1 method shows an average impact of 0.41 across c-squares (I-6) and only 46% (I-7), have impact scores less than 20% (I-7).

Maps of spatial distribution of intensity (surface abrasion), seafloor sensitivity and economic value and weight of fisheries landings are shown in Figure 1. Activity is mostly distributed across most of the Arkona and Bornholm Basin subregion (Figure 1).

Table 1

Table 1. Pressure and impact indicators for 2013-2018
Indicators	0 to 200 m	200 to 800 m	more than 800 m
Average intensity (I-1)	1.10	NA	NA
Proportion of area in fished cells (I-2)	0.78	NA	NA
Proportion of area fished per year (I-3)	0.42	NA	NA
Smallest prop. of area in fished cells with 90% of fishing effort (I-4)	0.31	NA	NA
Proportion of area in unfished cells (I-5)	0.22	NA	NA
Average PD impact (I-6)	0.02	NA	NA
Average L1 impact (I-6)	0.41	NA	NA
Proportion of area with PD impact < 0.2 (I-7)	0.99	NA	NA
Proportion of area with L1 impact < 0.2 (I-7)	0.46	NA	NA

Figure 1

Figure 1 Geographic distribution of surface abrasion, seabed sensitivity (community longevity) and total value and weight from mobile bottom-contacting gear. The maps of surface abrasion, value and weight show the average per year for 2013-2018

Pressure

Fishing intensity is relatively well distributed across the Arkona and Bornholm Basin subregion (Figure 2).

The proportion of area subject to fishing pressure is high across most broad-scale habitats, apart from the infralittoral mixed sediments and infralittoral coarse sediment (< 50%) (Table 2). The highest fishing intensity is found in the offshore circalittoral mud (2.66 yr-1), offshore circalittoral mixed sediment (2.76 yr-1) and offshore circalittoral sand (2.20 yr-1) (Table 2).

Figure 3 shows the fishing intensity for the four largest MSDF broad-scale habitats. Total fishing intensity peaked in 2012, and has been decreasing since (Figure 3). This trend is predominantly driven by the offshore circalittoral mud and circalittoral sand (Figure 3). The average trawling intensity has declined roughly in line with the proportion of area fished (Figure 3, compare left and middle panel). This shows that changes in intensity have also been linked to a decrease in spatial distribution of the footprint.

Fishing pressure is spatially distributed, both at the regional level as well as at the level of the habitat (Figure 3, right panel). The smallest proportion of habitat with 90% of effort is around 30%. The intensively fished areas represent the ‘core fishing grounds’. These grounds contribute most of the landings and value (Figure 4). More than 80% of the fishing effort (swept area), landings and value, occur in 20% of the surface area of the Baltic Proper (Figure 4).

Figure 2

Figure 2 Surface abrasion, Swept Area Ratio, by mobile bottom-contacting gears (year-1), averaged for the 2013-2018 six-year cycle

Table 2

Table 2 Overview of pressure indicators of all mobile bottom-contacting gears per broad-scale habitat averaged for 2013-2018. I refers to the indicators in Table 1.
MSFD broad habitat type	Extent of habitat (1000 km²)	Number of grid cells	Landings 1000 tonnes	Value 10⁶ euro	Swept area 1000 km²	Average intensity (I-1)	Prop. of area in fished grid cells (I-2)	Prop. of area fished per year (I-3)	Smallest prop. of area with 90% of fishing effort (I-4)
Offshore circalittoral mud	9.44	810	11.87	8.83	25.06	2.66	1.00	0.86	0.49
Circalittoral sand	8.58	1237	2.91	2.48	8.84	1.03	0.90	0.47	0.23
Offshore circalittoral mixed sediment	3.20	487	3.44	2.88	8.84	2.76	1.00	0.63	0.28
Infralittoral sand	11.86	1192	1.98	1.41	6.72	0.57	0.74	0.30	0.19
Circalittoral mixed sediment	10.03	1144	2.50	1.50	4.24	0.42	0.59	0.22	0.18
Circalittoral mud	1.99	479	1.46	1.23	3.27	1.64	0.98	0.67	0.32
Offshore circalittoral sand	1.47	315	1.31	1.01	3.22	2.20	0.98	0.71	0.37
Circalittoral mud or Circalittoral sand	1.23	189	0.65	0.38	1.03	0.83	0.92	0.50	0.33
Offshore circalittoral mud or Offshore circalittoral sand	1.38	168	0.28	0.22	0.75	0.55	1.00	0.26	0.36
Infralittoral coarse sediment	2.69	626	0.12	0.08	0.23	0.09	0.46	0.07	0.12
Circalittoral coarse sediment	1.30	519	0.06	0.06	0.21	0.16	0.60	0.11	0.11
Infralittoral mixed sediment	2.95	619	0.15	0.08	0.18	0.06	0.42	0.06	0.12
Infralittoral mud	0.24	93	0.03	0.03	0.16	0.69	0.71	0.40	0.17
Infralittoral rock and biogenic reef	0.49	146	0.01	0.01	0.04	0.07	0.58	0.07	0.09
Circalittoral rock and biogenic reef	0.05	66	0.01	0.01	0.02	0.42	0.84	0.37	0.08
Offshore circalittoral coarse sediment	0.02	30	0.01	0.01	0.01	0.58	0.97	0.41	0.30
Offshore circalittoral rock and biogenic reef	0.00	3	0.00	0.00	0.00	0.22	1.00	0.22	NA
Infralittoral mud or Infralittoral sand	0.00	13	0.00	0.00	0.00	0.00	0.00	0.00	NA

Figure 3

Figure 3. Time series of (a) mean fishing intensity (surface abrasion), (b) proportion of the surface area of the seafloor fished, (c) aggregation of fishing (proportion of the surface area with 90% of the fishing effort) by habitat. Results represent vessels over 15m (2009-2011) and vessels over 12m (2012-2018).

Figure 4

Figure 4. Cumulative proportion of the swept area, landings and value. Grid cells were sorted from highest to lowest fishing intensity and include non-fished cells. The results are for all mobile bottom-contacting gears based on averaged fishing data per c-square from 2013-2018.

Core fishing grounds

Core fishing grounds are defined as the c-squares with the 90% highest value of landings in the VMS data. Figure 5 shows the number of years c-squares are within the 90% highest value by métier. Only three métiers are used in the Arkona and Bornholm Basin subregion: otter trawls for cod and plaice (OT_DMF) and for small pelagic fish (OT_SPF), and seine for plaice and cod (SDN_DMF). If fishing in a métier occurs in the same c-square every year with high value of landings, the rightmost bar in Figure 5 will be high, meaning that the c-square is within the 90% highest value of landings every year during the period 2013-2018. If a c-square is only within the 90% highest value in one year, it will end up in the bar at the left. Figure 6 shows the percentage area overlap between the 90% highest value per year and the reference fishing ground. Both figures highlight that the fisheries for small pelagic fish (OT_SPF) and the seine (SDN_DMF) have the highest variation in space.

Figure 7 illustrates the relationship between area fished in percent and the cumulated value of landings, sorted from the c-squares with highest value fisheries. The curves are generally starting steeply, illustrating the concentration of the fisheries at fishing grounds and the curves are ending horizontally, illustrating the peripheral fisheries going on outside the main fishing grounds.

Figure 8 shows the area associated with each 10-percentile interval for each métier using averages of SAR (left column) and landings value (euro, right column) for the period 2013-2018.

Figure 5

Figure 5. Number of years c-squares are within the 90% highest value by métier, presented as a % relative to the total number of c-squares (n) that are within the 90% highest value by métier across all years. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 6

Figure 6. Percentage area overlap between the 90% highest value per year and the reference core fishing ground. For métiers that are included in Figure 5 and missing in Figure 6, no reference core ground could be established and/or métiers were not used in the area in some years.

Figure 7

Figure 7. Percent area fished vs. landings value (euro) by métier, coloured by year. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 8

Figure 8. The area associated with each 10-percentile interval for each métier using averages of SAR (left column) and landings value (euro, right column) for the period 2013-2018. The lightest blue c-squares represent the lowest 10% of total SAR / value of landings. The brown c-squares represent the highest 10% of total SAR / value of landings.

Fishing by métier

Intensity, weight and value of landings are estimated for the grid cells that were fished by one MBCG métier, ignoring cells fished by other métiers (Table 3).

Otter trawls for crustaceans (OT_CRU) and for small pelagic fish (OT_SPF) have the highest landings and value per area swept (Table 3).

Table 3

Table 3. Overview of area fished (sum of swept area), landings and value for the different metiers. Area fished in 1000 km², weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Area swept (1000 km2)	0	<0.005	59.15	0	1.40	2.26	0.02	0	0	0
Landings (1000 tonnes)	0	<0.005	24.07	0	2.60	0.14	<0.005	0	0	0
Value (10^6 euro)	0	<0.005	19.09	0	0.92	0.21	<0.005	0	0	0
Landings (1000 tonnes)/Area swept (1000 km2)	NaN	0.79	0.41	NaN	1.86	0.06	0.05	NaN	NaN	NaN
Value (10^6 euro)/Area swept (1000 km2)	NaN	0.78	0.32	NaN	0.66	0.09	0.08	NaN	NaN	NaN

Impact

The impact of mobile bottom-contacting fishing from the PD method shows areas of relatively uniformly distributed low fishing impact across the whole Arkona and Bornholm Basin subregion (Figure 9, left). High impact from the L1 method covers the same area, but shows a higher impact (Figure 9, right).

The impact scores for PD was constant and low over time, whereas the L1 impact scores followed the fishing intensity more closely, and decreased over time (Figure 10, left panel). Impact does not vary much between habitats for the PD method (Figure 9 shows the four most extensive habitat types), but is much higher for the offshore circalittoral mud in the L1 method. All habitat types (100%) have a PD impact score <0.2, whereas more than 50-60% of the infralittoral sand, circalittoral mixed sediment and circalittoral sand have an L1 impact score <0.2. Only ~10% of the offshore circalittoral mud has an L1 impact score <0.2, and this fraction increases to 50% by 2018 (Figure 10).

Table 4 shows impact per métier relative to weight and value of landings. In this analysis, the different métiers are assessed for the grid cells that were fished by one MBCG métier, ignoring cells fished by other métiers. As such this estimates the maximum impact compared to the untrawled situation and the impact estimated assuming all other métiers to have impacted the habitat will be less than this. Otter trawls for crustaceans (OT_CRU) have the highest value per impact in the Arkona and Bornholm Basin subregion (Table 3).

Impact by all métiers shows that otter trawls for cod or plaice has the highest impact for each habitat type (Figure 11).

Figure 9

Figure 9. Impact of mobile bottom-contacting gears averaged for the 2013-2018 six-year cycle for the PD and L1 method.

Figure 10

Figure 10. The mean impact of mobile bottom-contacting gears in all combined MSFD habitats and the four most extensive habitat types between 2009 and 2018 (left). The proportion of the fished area with an impact of less than 0.2 (right)

Table 4

Table 4. Overview of impact per metier relative to weight and value of landings estimated for the grid cells fished (SAR >0) with these métiers only. Weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Landings (1000 tonnes)/PD impact	NA	0.125	0.355	NA	2.702	0.125	0.053	NA	NA	NA
Value (10^6 euro)/PD impact	NA	0.123	0.281	NA	0.956	0.179	0.082	NA	NA	NA
Landings (1000 tonnes)/L1 impact	NA	0.158	0.019	NA	0.033	0.003	0.001	NA	NA	NA
Value (10^6 euro)/L1 impact	NA	0.155	0.015	NA	0.012	0.005	0.001	NA	NA	NA

Figure 11

Figure 11. PD impact (upper panel) and L1 impact (lower panel) of selected gear groupings on the most extensive MSFD habitat types. Impact is estimated in isolation of the other gear groupings. Note the different scales on the Y-axis.

Management scenarios

The figures and tables below show one implementation of multi-purpose habitat management through reductions in effort and spatial closures for the four most extensive MSFD habitat types. They show the changes in average impact (PD, L1), unfished area and fisheries values of landings based on a static assessment of effort removal.

The analysis is based on the progressive removal of 5 to 99% of all MBCG fishing effort, starting from the c-squares with the lowest effort (corrected for the areal extent of the MSFD habitat within each c-square). Blue dots show the current situation and are used as reference. The % of unfished area in the reference is only based on grid cells that are unfished. Average PD and L1 impacts are a weighted average and consider the areal extent of each MSFD habitat type within a grid cell.

Note that the fraction of grid cells above/below a certain impact threshold initially remains the same (not shown) as the removal of effort starts from the c-squares with the lowest effort that typically have low impact.

MSFD habitat - 1

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.05	0.79	0.02	100.00	100.00
5	0.05	0.68	23.85	94.68	94.69
10	0.05	0.59	35.56	88.67	88.98
15	0.04	0.51	45.15	82.66	83.97
20	0.04	0.45	52.00	76.70	78.61
30	0.04	0.35	62.96	65.54	68.52
40	0.03	0.27	71.33	55.41	59.32
60	0.02	0.15	83.65	37.11	39.40
80	0.01	0.06	93.38	18.46	18.69
99	0.00	0.00	100.00	0.90	0.76

MSFD habitat - 2

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.02	0.49	10.16	100.00	100.00
5	0.02	0.43	48.23	94.19	93.87
10	0.02	0.37	58.12	89.07	88.91
15	0.02	0.32	64.86	83.75	83.79
20	0.02	0.28	69.80	77.70	78.39
30	0.01	0.22	77.59	67.34	68.14
40	0.01	0.16	83.57	54.93	56.88
60	0.01	0.10	90.36	35.89	36.93
80	0.00	0.04	96.05	17.04	17.21
99	0.00	0.00	100.00	1.12	0.71

MSFD habitat - 3

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.05	0.62	0.25	100.00	100.00
5	0.05	0.49	42.91	94.87	94.50
10	0.05	0.39	57.57	90.33	89.98
15	0.04	0.32	65.82	86.05	85.42
20	0.04	0.27	71.70	81.34	80.12
30	0.04	0.19	80.80	71.88	69.92
40	0.03	0.13	86.95	62.94	59.49
60	0.02	0.06	94.10	44.57	40.25
80	0.01	0.03	97.79	22.51	20.64
99	0.00	0.01	100.00	4.58	4.29

MSFD habitat - 4

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.01	0.29	25.89	100.00	100.00
5	0.01	0.25	61.06	87.30	86.80
10	0.01	0.22	70.00	80.10	80.49
15	0.01	0.19	76.53	72.95	73.58
20	0.01	0.16	81.08	66.89	68.62
30	0.01	0.12	86.25	53.87	53.08
40	0.01	0.09	90.04	43.21	41.86
60	0.00	0.05	95.19	25.40	24.39
80	0.00	0.02	98.32	12.04	12.72
99	0.00	0.00	100.00	2.05	2.99

Overview all MSFD habitats

Fishing effort consequences, as a % relative to total swept area, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Offshore circalittoral mud	9.44	0.3	0.9	3.5	7.8	12.3	18.6	27.3	38.4	53.4	73.1
Circalittoral sand	8.58	0.0	0.0	0.2	0.8	2.7	5.8	11.3	20.5	33.7	59.0
Offshore circalittoral mixed sediment	3.2	0.2	0.4	1.5	2.7	4.4	7.1	11.0	19.0	28.6	46.6
Infralittoral sand	11.86	0.0	0.0	0.0	<0.1	0.4	1.7	4.6	10.1	18.9	40.2
Circalittoral mixed sediment	10.03	0.0	0.0	0.0	0.0	0.0	0.2	1.1	5.1	14.7	32.5
Circalittoral mud	1.99	<0.1	0.4	2.3	5.0	10.4	16.2	23.8	34.8	48.5	68.8
Offshore circalittoral sand	1.47	<0.1	0.3	1.3	3.6	8.0	17.7	27.2	41.3	56.7	78.3
Circalittoral mud or Circalittoral sand	1.23	0.0	<0.1	0.6	1.6	5.5	11.8	18.4	27.9	41.4	61.1
Offshore circalittoral mud or Offshore circalittoral sand	1.38	0.2	0.4	1.7	2.9	4.9	8.1	11.4	16.4	22.0	31.9
Infralittoral coarse sediment	2.69	0.0	0.0	0.0	0.0	0.0	0.0	0.6	2.1	5.3	19.6
Circalittoral coarse sediment	1.3	0.0	0.0	0.0	0.0	0.0	0.8	2.0	3.7	8.6	22.0
Infralittoral mixed sediment	2.95	0.0	0.0	0.0	0.0	0.0	0.0	0.2	2.1	6.2	23.8
Infralittoral mud	0.24	0.0	0.0	0.0	<0.1	1.1	4.1	11.5	18.2	51.3	79.0
Infralittoral rock and biogenic reef	0.49	0.0	0.0	0.0	0.0	0.0	1.5	2.7	4.4	7.1	13.8
Circalittoral rock and biogenic reef	0.05	0.0	0.0	<0.1	0.8	1.7	19.6	33.1	61.8	61.8	100.0
Offshore circalittoral coarse sediment	0.02	0.1	0.4	0.8	1.7	4.8	13.9	25.1	31.6	70.7	100.0
Offshore circalittoral rock and biogenic reef	0	0.2	11.7	11.7	11.7	11.7	11.7	11.7	100.0	100.0	100.0
Infralittoral mud or Infralittoral sand	0	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Fishing value consequences, as a % relative to total value, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Offshore circalittoral mud	9.44	0.4	1.0	3.7	8.7	14.3	21.6	31.8	42.8	56.6	75.2
Circalittoral sand	8.58	0.0	0.0	0.3	1.3	3.5	6.7	12.4	23.0	36.4	63.6
Offshore circalittoral mixed sediment	3.2	0.2	0.5	1.7	2.9	4.5	7.1	10.6	17.9	26.9	43.3
Infralittoral sand	11.86	0.0	0.0	0.0	0.2	1.1	5.2	12.2	20.1	31.5	57.1
Circalittoral mixed sediment	10.03	0.0	0.0	0.0	0.0	0.0	0.3	1.1	5.5	17.4	37.9
Circalittoral mud	1.99	0.1	0.8	3.1	6.2	12.3	19.1	27.5	38.4	55.9	74.0
Offshore circalittoral sand	1.47	<0.1	0.5	1.8	4.5	9.8	20.4	29.7	43.3	58.0	78.3
Circalittoral mud or Circalittoral sand	1.23	0.0	<0.1	0.7	2.3	7.7	14.9	20.3	33.0	50.4	69.4
Offshore circalittoral mud or Offshore circalittoral sand	1.38	0.3	0.6	2.2	3.4	5.4	8.9	12.7	18.0	24.2	34.4
Infralittoral coarse sediment	2.69	0.0	0.0	0.0	0.0	0.0	0.0	1.0	3.3	8.2	24.9
Circalittoral coarse sediment	1.3	0.0	0.0	0.0	0.0	0.0	1.2	3.2	5.3	12.1	28.5
Infralittoral mixed sediment	2.95	0.0	0.0	0.0	0.0	0.0	0.0	0.3	1.7	5.5	21.6
Infralittoral mud	0.24	0.0	0.0	0.0	0.2	4.5	13.6	25.8	38.1	70.1	89.9
Infralittoral rock and biogenic reef	0.49	0.0	0.0	0.0	0.0	0.0	2.0	2.9	4.4	9.9	18.1
Circalittoral rock and biogenic reef	0.05	0.0	0.0	<0.1	1.1	2.1	24.8	35.8	67.1	67.1	100.0
Offshore circalittoral coarse sediment	0.02	<0.1	0.4	0.7	1.8	4.9	13.1	25.2	34.3	72.6	100.0
Offshore circalittoral rock and biogenic reef	0	0.0	3.7	3.7	3.7	3.7	3.7	3.7	100.0	100.0	100.0
Infralittoral mud or Infralittoral sand	0	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Fishing weight consequences, as a % relative to total weight, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Offshore circalittoral mud	9.44	0.4	1.1	3.8	8.5	13.4	19.9	28.9	39.1	53.1	74.2
Circalittoral sand	8.58	0.0	0.0	0.4	1.6	3.9	7.0	12.4	22.1	35.6	62.4
Offshore circalittoral mixed sediment	3.2	0.3	0.6	2.1	3.3	4.9	7.5	10.9	19.1	28.9	47.9
Infralittoral sand	11.86	0.0	0.0	0.0	0.2	1.0	5.9	12.8	19.7	30.1	58.3
Circalittoral mixed sediment	10.03	0.0	0.0	0.0	0.0	0.0	0.2	0.9	5.1	17.7	40.4
Circalittoral mud	1.99	0.2	1.2	4.6	8.7	15.4	21.2	28.5	37.5	53.0	70.2
Offshore circalittoral sand	1.47	0.1	0.8	1.8	3.9	8.4	17.7	26.2	39.2	54.3	75.1
Circalittoral mud or Circalittoral sand	1.23	0.0	<0.1	0.9	2.6	9.0	16.5	19.9	34.1	54.2	73.0
Offshore circalittoral mud or Offshore circalittoral sand	1.38	0.4	0.9	2.9	4.2	6.3	10.0	14.2	19.6	25.8	35.1
Infralittoral coarse sediment	2.69	0.0	0.0	0.0	0.0	0.0	0.0	0.7	2.4	6.1	18.3
Circalittoral coarse sediment	1.3	0.0	0.0	0.0	0.0	0.0	1.5	3.2	5.8	12.3	26.2
Infralittoral mixed sediment	2.95	0.0	0.0	0.0	0.0	0.0	0.0	0.1	0.9	3.5	15.5
Infralittoral mud	0.24	0.0	0.0	0.0	0.4	7.5	20.6	34.6	45.4	76.2	90.8
Infralittoral rock and biogenic reef	0.49	0.0	0.0	0.0	0.0	0.0	2.0	2.7	3.9	8.5	19.2
Circalittoral rock and biogenic reef	0.05	0.0	0.0	<0.1	1.0	1.9	17.5	32.1	66.5	66.5	100.0
Offshore circalittoral coarse sediment	0.02	<0.1	0.4	0.6	1.6	4.7	12.9	24.0	31.4	74.4	100.0
Offshore circalittoral rock and biogenic reef	0	<0.1	8.4	8.4	8.4	8.4	8.4	8.4	100.0	100.0	100.0
Infralittoral mud or Infralittoral sand	0	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Western Baltic Sea

Summary

The physical disturbance pressures from mobile bottom-contacting fishing gears is spatially variable across the western Baltic Sea subdivision with 61% of the grid cells (I-2), and 29% of the surface area (I-3), in the depth zone 0-200m, being fished on average per year for the period 2013-2018 (Table 1). Fishing is aggregated with 90% of the pressure occurring in 21% of grid cells (I-4).

The PD method shows an average decline in community biomass of 2% relative to carrying capacity across c-squares (I-6). Virtually all c-squares (99% (I-7)), have an impact score less than 20%. The L1 method shows an average impact of 0.30 across c-squares (I-6) and only 61% (I-7), have impact scores less than 20% (I-7).

Maps of spatial distribution of intensity (surface abrasion), seafloor sensitivity and economic value and weight of fisheries landings are shown in Figure 1. Activity is mostly distributed across the southern part of the western Baltic Sea subregion (Figure 1).

Table 1

Table 1. Pressure and impact indicators for 2013-2018
Indicators	0 to 200 m	200 to 800 m	more than 800 m
Average intensity (I-1)	0.77	NA	NA
Proportion of area in fished cells (I-2)	0.61	NA	NA
Proportion of area fished per year (I-3)	0.29	NA	NA
Smallest prop. of area in fished cells with 90% of fishing effort (I-4)	0.21	NA	NA
Proportion of area in unfished cells (I-5)	0.39	NA	NA
Average PD impact (I-6)	0.02	NA	NA
Average L1 impact (I-6)	0.30	NA	NA
Proportion of area with PD impact < 0.2 (I-7)	0.99	NA	NA
Proportion of area with L1 impact < 0.2 (I-7)	0.61	NA	NA

Figure 1

Figure 1 Geographic distribution of surface abrasion, seabed sensitivity (community longevity) and total value and weight from mobile bottom-contacting gear. The maps of surface abrasion, value and weight show the average per year for 2013-2018

Pressure

Fishing intensity is mostly located in the southern part of the western Baltic Sea subregion (Figure 2).

The proportion of area subject to fishing pressure is high across most broad-scale habitats, apart from the infralittoral mixed sediments and infralittoral mud (< 50%) (Table 2). The highest fishing intensity is found in the offshore circalittoral mud (2.99 yr-1), circalittoral mud (2.16 yr-1) (Table 2).

Figure 3 shows the fishing intensity for the four largest MSDF broad-scale habitats. Total fishing intensity has been decreasing since 2010 (Figure 3). This trend is the same for all broad-scale habitat types (Figure 3). The average trawling intensity has declined roughly in line with the proportion of area fished (Figure 3, compare left and middle panel). This shows that changes in intensity have also been linked to a decrease in spatial distribution of the footprint.

Fishing pressure is spatially distributed, both at the regional level as well as at the level of the habitat (Figure 3, right panel). The smallest proportion of habitat with 90% of effort is between 10 and 30%. The intensively fished areas represent the ‘core fishing grounds’. These grounds contribute most of the landings and value (Figure 4). More than 80% of the fishing effort (swept area), landings and value, occur in 20% of the surface area of the western Baltic Sea subregion (Figure 4).

Figure 2

Figure 2 Surface abrasion, Swept Area Ratio, by mobile bottom-contacting gears (year-1), averaged for the 2013-2018 six-year cycle

Table 2

Table 2 Overview of pressure indicators of all mobile bottom-contacting gears per broad-scale habitat averaged for 2013-2018. I refers to the indicators in Table 1.
MSFD broad habitat type	Extent of habitat (1000 km²)	Number of grid cells	Landings 1000 tonnes	Value 10⁶ euro	Swept area 1000 km²	Average intensity (I-1)	Prop. of area in fished grid cells (I-2)	Prop. of area fished per year (I-3)	Smallest prop. of area with 90% of fishing effort (I-4)
Infralittoral sand	7.37	927	1.28	1.56	4.14	0.56	0.55	0.21	0.14
Circalittoral mud	1.78	286	1.82	2.09	3.85	2.16	0.93	0.74	0.27
Circalittoral sand	1.94	524	1.26	1.50	2.99	1.54	0.77	0.50	0.18
Offshore circalittoral mud	0.21	56	0.17	0.20	0.63	2.99	0.99	0.90	0.23
Infralittoral mixed sediment	2.95	615	0.21	0.28	0.60	0.20	0.48	0.11	0.13
Infralittoral mud	1.05	326	0.27	0.33	0.52	0.50	0.47	0.21	0.13
Circalittoral mixed sediment	0.45	296	0.14	0.19	0.35	0.79	0.81	0.35	0.17
Offshore circalittoral sand	0.21	135	0.10	0.13	0.28	1.35	0.85	0.50	0.25
Infralittoral coarse sediment	0.66	207	0.13	0.16	0.26	0.40	0.76	0.23	0.25
Circalittoral coarse sediment	0.05	76	0.06	0.07	0.11	1.97	0.92	0.73	0.30
Offshore circalittoral mixed sediment	0.05	76	0.01	0.02	0.03	0.73	0.81	0.24	0.17
Offshore circalittoral coarse sediment	0.00	8	0.00	0.00	0.00	0.45	1.00	0.43	NA
Infralittoral rock and biogenic reef	0.02	3	0.00	0.00	0.00	0.00	0.00	0.00	NA

Figure 3

Figure 3. Time series of (a) mean fishing intensity (surface abrasion), (b) proportion of the surface area of the seafloor fished, (c) aggregation of fishing (proportion of the surface area with 90% of the fishing effort) by habitat. Results represent vessels over 15m (2009-2011) and vessels over 12m (2012-2018).

Figure 4

Figure 4. Cumulative proportion of the swept area, landings and value. Grid cells were sorted from highest to lowest fishing intensity and include non-fished cells. The results are for all mobile bottom-contacting gears based on averaged fishing data per c-square from 2013-2018.

Core fishing grounds

Core fishing grounds are defined as the c-squares with the 90% highest value of landings in the VMS data. Figure 5 shows the number of years c-squares are within the 90% highest value by métier. Only three métiers are used in the western Baltic Sea subregion: otter trawls for cod and plaice (OT_DMF) and for small pelagic fish (OT_SPF), and seine for plaice and cod (SDN_DMF). If fishing in a métier occurs in the same c-square every year with high value of landings, the rightmost bar in Figure 5 will be high, meaning that the c-square is within the 90% highest value of landings every year during the period 2013-2018. If a c-square is only within the 90% highest value in one year, it will end up in the bar at the left.

Figure 8 shows the area associated with each 10-percentile interval for each métier using averages of SAR (left column) and landings value (euro, right column) for the period 2013-2018.

Figure 5

Figure 5. Number of years c-squares are within the 90% highest value by métier, presented as a % relative to the total number of c-squares (n) that are within the 90% highest value by métier across all years. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 6

Figure 6. Percentage area overlap between the 90% highest value per year and the reference core fishing ground. For métiers that are included in Figure 5 and missing in Figure 6, no reference core ground could be established and/or métiers were not used in the area in some years.

Figure 7

Figure 7. Percent area fished vs. landings value (euro) by métier, coloured by year. The outcome is only shown for métiers that have >50 uniquely fished c-squares in the period 2013-2018.

Figure 8

Figure 8. The area associated with each 10-percentile interval for each métier using averages of SAR (left column) and landings value (euro, right column) for the period 2013-2018. The lightest blue c-squares represent the lowest 10% of total SAR / value of landings. The brown c-squares represent the highest 10% of total SAR / value of landings.

Fishing by métier

Intensity, weight and value of landings are estimated for the grid cells that were fished by one MBCG métier, ignoring cells fished by other métiers (Table 3).

Otter trawls for crustaceans (OT_CRU) and for small pelagic fish (OT_SPF) have the highest landings and value per area swept (Table 3).

Table 3

Table 3. Overview of area fished (sum of swept area), landings and value for the different metiers. Area fished in 1000 km², weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Area swept (1000 km2)	0	<0.005	10.97	0	0.06	2.82	<0.005	0	0	0
Landings (1000 tonnes)	0	<0.005	4.97	0	0.26	0.25	<0.005	0	0	0
Value (10^6 euro)	0	<0.005	6.13	0	0.08	0.36	<0.005	0	0	0
Landings (1000 tonnes)/Area swept (1000 km2)	NaN	0.3	0.45	NaN	4.31	0.09	0.03	NaN	NaN	NaN
Value (10^6 euro)/Area swept (1000 km2)	NaN	1.22	0.56	NaN	1.35	0.13	0.05	NaN	NaN	NaN

Impact

The impact of mobile bottom-contacting fishing from the PD method shows areas of relatively uniformly distributed low fishing impact across the western Baltic Sea subregion (Figure 9, left). High impact from the L1 method is mostly located in the southern part of the western Baltic Sea subregion, but shows a higher impact (Figure 9, right).

The impact scores for PD was constant and low over time, whereas the L1 impact scores followed the fishing intensity more closely, and decreased over time (Figure 10, left panel). Impact does not vary much between habitats for the PD method (Figure 9 shows the four most extensive habitat types), but is much higher for the circalittoral mud with the L1 method. Virtually all habitat types (100%) have a PD impact score <0.2, whereas more this is much more distributed for the L1 impact score (Figure 10).

Table 4 shows impact per métier relative to weight and value of landings. In this analysis, the different métiers are assessed for the grid cells that were fished by one MBCG métier, ignoring cells fished by other métiers. As such this estimates the maximum impact compared to the untrawled situation and the impact estimated assuming all other métiers to have impacted the habitat will be less than this. Otter trawls for crustaceans (OT_CRU) have the highest value per impact in the western Baltic Sea subregion (Table 3).

Impact by all métiers shows that otter trawls for cod or plaice has the highest impact for each habitat type (Figure 11).

Figure 9

Figure 9. Impact of mobile bottom-contacting gears averaged for the 2013-2018 six-year cycle for the PD and L1 method.

Figure 10

Figure 10. The mean impact of mobile bottom-contacting gears in all combined MSFD habitats and the four most extensive habitat types between 2009 and 2018 (left). The proportion of the fished area with an impact of less than 0.2 (right)

Table 4

Table 4. Overview of impact per metier relative to weight and value of landings estimated for the grid cells fished (SAR >0) with these métiers only. Weight of landings in 1000 tonnes, value of landings in 10⁶ euro.
	DRB_MOL	OT_CRU	OT_DMF	OT_MI	OT_SPF	SDN_DMF	SSC_DMF	TBB_CRU	TBB_DMF	TBB_MOL
Landings (1000 tonnes)/PD impact	NA	0.018	0.290	NA	2.272	0.171	0.019	NA	NA	NA
Value (10^6 euro)/PD impact	NA	0.072	0.358	NA	0.710	0.244	0.033	NA	NA	NA
Landings (1000 tonnes)/L1 impact	NA	0.018	0.018	NA	0.051	0.006	0.000	NA	NA	NA
Value (10^6 euro)/L1 impact	NA	0.074	0.022	NA	0.016	0.009	0.001	NA	NA	NA

Figure 11

Figure 11. PD impact (upper panel) and L1 impact (lower panel) of selected gear groupings on the most extensive MSFD habitat types. Impact is estimated in isolation of the other gear groupings. Note the different scales on the Y-axis.

Management scenarios

The figures and tables below show one implementation of multi-purpose habitat management through reductions in effort and spatial closures for the four most extensive MSFD habitat types. They show the changes in average impact (PD, L1), unfished area and fisheries values of landings based on a static assessment of effort removal.

The analysis is based on the progressive removal of 5 to 99% of all MBCG fishing effort, starting from the c-squares with the lowest effort (corrected for the areal extent of the MSFD habitat within each c-square). Blue dots show the current situation and are used as reference. The % of unfished area in the reference is only based on grid cells that are unfished. Average PD and L1 impacts are a weighted average and consider the areal extent of each MSFD habitat type within a grid cell.

Note that the fraction of grid cells above/below a certain impact threshold initially remains the same (not shown) as the removal of effort starts from the c-squares with the lowest effort that typically have low impact.

MSFD habitat - 1

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.01	0.22	44.58	100.00	100.00
5	0.01	0.19	75.31	91.26	89.95
10	0.01	0.15	81.69	82.78	81.84
15	0.01	0.13	85.32	74.46	71.95
20	0.01	0.10	87.97	66.21	63.63
30	0.01	0.07	91.70	49.35	46.68
40	0.00	0.05	94.39	37.20	34.31
60	0.00	0.03	97.20	22.02	19.05
80	0.00	0.01	99.51	10.16	8.12
99	0.00	0.00	100.00	5.82	4.49

MSFD habitat - 2

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.06	0.77	6.95	100.00	100.00
5	0.05	0.66	32.69	94.44	93.75
10	0.05	0.58	41.09	89.25	88.39
15	0.05	0.51	50.17	83.58	82.70
20	0.04	0.45	54.85	77.96	76.81
30	0.04	0.37	63.74	66.76	65.63
40	0.03	0.29	71.86	56.30	55.13
60	0.02	0.16	84.69	36.14	35.68
80	0.01	0.07	94.04	18.98	19.38
99	0.00	0.01	100.00	3.11	3.52

MSFD habitat - 3

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.04	0.51	22.78	100.00	100.00
5	0.04	0.42	53.82	94.40	93.42
10	0.04	0.36	61.03	88.91	86.67
15	0.03	0.31	66.77	83.19	80.92
20	0.03	0.28	70.68	78.08	75.80
30	0.03	0.22	77.68	68.25	65.90
40	0.02	0.16	83.71	59.53	56.42
60	0.02	0.09	91.91	41.36	37.21
80	0.01	0.03	97.46	19.30	17.39
99	0.00	0.01	100.00	5.56	3.48

MSFD habitat - 4

Multi-purpose habitat management trade-off for the most extensive MSFD habitat type.

Table presenting a similar overview as above, while including weight of landings
Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0.08	0.92	1.21	100.00	100.00
5	0.07	0.81	18.85	93.43	92.84
10	0.07	0.68	33.34	88.97	88.55
15	0.06	0.63	37.95	84.65	84.29
20	0.06	0.58	48.89	78.95	78.59
30	0.05	0.45	57.79	68.40	68.51
40	0.05	0.42	62.02	60.18	60.52
60	0.03	0.30	78.63	43.93	44.68
80	0.02	0.14	93.30	25.04	25.85
99	0.01	0.07	100.00	14.45	14.95

Overview all MSFD habitats

Fishing effort consequences, as a % relative to total swept area, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Infralittoral sand	7.37	0.0	0.0	0.0	0.0	0.0	<0.1	0.6	2.6	8.4	25.1
Circalittoral mud	1.78	0.0	<0.1	1.1	4.3	9.8	15.0	26.4	38.6	53.3	72.5
Circalittoral sand	1.94	0.0	0.0	0.0	<0.1	0.8	3.6	9.3	19.3	33.9	57.3
Offshore circalittoral mud	0.21	0.4	1.6	6.0	9.7	19.1	30.0	45.2	53.8	73.9	85.3
Infralittoral mixed sediment	2.95	0.0	0.0	0.0	0.0	0.0	0.0	0.4	1.7	4.8	18.7
Infralittoral mud	1.05	0.0	0.0	0.0	0.0	0.0	0.0	0.3	1.9	12.1	34.7
Circalittoral mixed sediment	0.45	0.0	0.0	<0.1	0.2	0.8	1.6	5.6	15.3	28.0	63.4
Offshore circalittoral sand	0.21	0.0	0.0	<0.1	0.4	2.8	6.8	12.8	23.1	36.9	56.0
Infralittoral coarse sediment	0.66	0.0	0.0	0.0	0.2	1.3	3.3	5.5	10.1	21.2	41.6
Circalittoral coarse sediment	0.05	0.0	<0.1	1.7	6.4	9.9	14.5	24.8	38.7	59.5	76.2
Offshore circalittoral mixed sediment	0.05	0.0	0.0	<0.1	0.4	0.4	0.6	1.3	3.8	12.2	40.3
Offshore circalittoral coarse sediment	0	4.6	30.9	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Infralittoral rock and biogenic reef	0.02	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Fishing value consequences, as a % relative to total value, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Infralittoral sand	7.37	0.0	0.0	0.0	0.0	0.0	0.2	1.1	4.5	14.6	41.9
Circalittoral mud	1.78	0.0	<0.1	1.0	4.9	10.8	16.9	29.1	42.8	58.2	76.5
Circalittoral sand	1.94	0.0	0.0	0.0	0.1	0.9	4.3	10.5	21.5	35.0	56.6
Offshore circalittoral mud	0.21	0.5	2.2	8.0	11.0	21.1	31.6	48.0	56.1	75.0	85.5
Infralittoral mixed sediment	2.95	0.0	0.0	0.0	0.0	0.0	0.0	0.6	1.8	4.4	17.4
Infralittoral mud	1.05	0.0	0.0	0.0	0.0	0.0	0.0	0.2	1.7	11.6	34.8
Circalittoral mixed sediment	0.45	0.0	0.0	<0.1	0.2	0.7	1.5	4.7	12.9	25.6	56.0
Offshore circalittoral sand	0.21	0.0	0.0	<0.1	0.3	2.8	6.6	12.3	24.8	37.6	55.5
Infralittoral coarse sediment	0.66	0.0	0.0	0.0	0.7	2.4	5.2	8.3	15.5	35.9	62.5
Circalittoral coarse sediment	0.05	0.0	<0.1	1.7	7.5	11.6	15.9	33.6	47.3	68.5	81.4
Offshore circalittoral mixed sediment	0.05	0.0	0.0	<0.1	0.3	0.3	0.5	1.0	2.8	10.0	37.9
Offshore circalittoral coarse sediment	0	5.3	29.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Infralittoral rock and biogenic reef	0.02	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Fishing weight consequences, as a % relative to total weight, of protecting a certain fraction of each broad habitat type sorted from low to high fished c-squares
MSFD broad habitat type	Extent of habitat 1000 km²	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
Infralittoral sand	7.37	0.0	0.0	0.0	0.0	0.0	0.2	1.7	5.4	15.7	44.8
Circalittoral mud	1.78	0.0	<0.1	1.6	5.5	11.6	17.8	30.5	43.9	58.9	76.5
Circalittoral sand	1.94	0.0	0.0	0.0	0.2	1.3	5.1	12.6	23.7	38.0	60.5
Offshore circalittoral mud	0.21	1.2	2.8	8.6	11.4	21.4	31.5	47.4	55.3	74.1	85.1
Infralittoral mixed sediment	2.95	0.0	0.0	0.0	0.0	0.0	0.0	1.1	3.9	8.0	21.5
Infralittoral mud	1.05	0.0	0.0	0.0	0.0	0.0	0.0	0.3	2.5	12.7	36.2
Circalittoral mixed sediment	0.45	0.0	0.0	<0.1	0.4	0.9	2.0	6.3	14.2	27.2	56.3
Offshore circalittoral sand	0.21	0.0	0.0	<0.1	0.3	4.5	8.8	18.3	39.8	53.6	67.0
Infralittoral coarse sediment	0.66	0.0	0.0	0.0	0.6	2.5	5.4	8.3	17.2	36.2	63.2
Circalittoral coarse sediment	0.05	0.0	<0.1	2.2	7.8	12.0	16.0	33.2	49.1	69.3	81.1
Offshore circalittoral mixed sediment	0.05	0.0	0.0	<0.1	0.8	0.8	1.0	1.6	5.0	15.8	44.4
Offshore circalittoral coarse sediment	0	6.2	35.9	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
Infralittoral rock and biogenic reef	0.02	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN	NaN

Read me

ICES developed an assessment of fishing footprint of mobile bottom-contacting fishing gears (MBCG) and benthic impact that is appropriate for a six-year management cycle of MSFD assessments. The assessment maps and pressure and impact indicator values produced are based on an average fishing intensity of 2013-2018. This assessment period is linked to the latest available fishing data, rather than to the MSFD Art 8 assessment periods. The assessment product further shows year-to-year variation in pressure and impact from 2009.

The assessment presents five pressure indicators and two benthic impact indicators by (sub-)regional, subdivision sea, or broadscale habitat type within that sea (Table 1), following ICES 2017 advice. The assessment further describes spatial and temporal variation of core MBCG fishing footprints. Lastly, the assessment describes a trade-off analysis between fisheries and the seafloor based on a management scenario where fishing effort is reduced through spatial closures in each broadscale habitat type.

Table 1. Pressure and impact indicators that are applied by (sub-)regional, subdivision sea, or broadscale habitat type within that sea at a 0.05° × 0.05° grid, hereafter termed c-square.
Indicators	Description
Intensity (I-1)	Average number of times the area is swept per year by MBCG. Estimated as the sum of swept area for all MBCG (averaged for the six-year cycle), divided by the total area.
Proportion of grid cells fished (I-2)	The number of c-squares fished at least once in the six-year cycle (irrespective of the swept area within the cell), divided by the total number of c-squares.
Proportion of area fished (I-3)	The sum of swept area across all c-squares based on the average for the six-year cycle, where swept area in a specific grid cell cannot be greater than the area of that grid cell, divided by the summed area of all c-squares.
Aggregation of fishing pressure (I-4)	The smallest proportion of c-squares in the area where 90% of the total swept area occurs.
Persistently unfished areas (I-5)	The number of c-squares persistently unfished in the six-year cylce (irrespective of the swept area within the cell), divided by the total number of c-squares.

Impact (I-6)	Average fishing impact across c-squares (averaged for the six-year cycle).
Proportion area with impact <0.2 (I-7)	The proportion of c-squares with an average impact below 0.2 (averaged for the six-year cycle)

Data limitations in Baltic Sea region

No fishing activity data is available from Russia.

Temporal patterns in fishing activity are available from 2009 for vessels over 15m and from 2012 for vessels over 12m. Temporal variation in fishing activity hence represents vessels over 15m (2009-2011) and vessels over 12m (2012-2018). The assessment maps and indicator values produced are based on an average for 2013-2018.

How are changes in the fishing footprint analyzed?

To describe the fishing footprint, we expressed fishing intensity as swept-area ratios (SAR). The swept area is calculated as hours fished x average fishing speed x gear width. The gear width is estimated based on relationships between average gear widths and average vessel length or engine power (kW), as stated in Eigaard et al. (2016) and using ICES expert input. The swept-area ratio is the sum of the swept area divided by the area of each grid cell (c-square). Therefore, the C-square SAR value indicates the theoretical number of times the entire grid cell has been swept if effort was evenly distributed within the cell. For example, a SAR of 2 means that each location within the c-square is fished 2 times over the year, a SAR of 0.5 means that each location within the c-square is fished once in two years. Due to data availability, all analyses of the fishing footprint do not account for sub-grid variation of fishing events within the c-square.

In order to better understand the relationship between catch/value of landings and the levels of physical disturbance for MSFD purposes, the analysis considers ten gear groupings (hereafter termed métiers) together with the total intensity of all gears (Table 2).

Table 2 Gear groupings used in the analysis. Note that OT_CRU includes OT_MIX_CRU and OT_MIX_CRU_DMF, and, OT_MIX includes OT_MIX_DMF_BEN and OT_MIX_DMF_PEL.
Métier	Main gear type	Target species assemblage group	Main target species	Depletion rate
DRB_MOL	Dredge	Molluscs	Scallops	0.200
OT_CRU	Otter trawl	Crustaceans	Nephrops, Pandalus, mixed fish	0.100
OT_DMF	Otter trawl	Demersal fish	Cod or plaice	0.026
OT_MIX	Otter trawl	Mixed fish	Mixed fish	0.074
OT_SPF	Otter trawl	Small pelagic fish	Sprat or sandeel	0.009
SDN_DMF	Danish seine	Demersal fish	Plaice, cod	0.009
SSC_DMF	Flyshooter (seine)	Demersal fish	Cod, haddock, flatfish	0.016
TBB_CRU	Beam trawl	Crustaceans	Brown shrimp	0.060
TBB_DMF	Beam trawl	Demersal fish	Flatfish	0.140
TBB_MOL	Beam trawl	Molluscs	Whelk, snails and scallops	0.060

How is benthic impact evaluated?

Two indicators of benthic impact were used.

The first indicator of impact estimates the amount of benthic biomass, relative to carrying capacity, which will not exist in the ecosystem if the current trawling intensity continues for a long time. This indicator is estimated using a population dynamic (PD) method (Pitcher et al., 2017, ICES 2018, Hiddink et al., 2019). The PD method uses explicit estimates of the removal of benthos by a single trawl event, and explicitly relates longevity to recovery rates. These parameters were estimated from all globally available trawl impact studies for infauna and epifauna (Hiddink et al. 2017, 2019). The PD method combines information on total benthic biomass (which is linked to the overall functioning of the ecosystem, see WGFBIT report 2018 section 3.2.1 on page 57) with the relative abundance of different longevity classes that in turn relates to the structure and biodiversity. For the calculation of PD-impact, the depletion of benthos by a single trawl event will differ between the different métiers based on the penetration depth of the métiers (Table 2, see further Hiddink et al. 2017, Rijnsdorp et al. 2020).

The PD method does not account for declines of rare and vulnerable species that managers may want to protect (e.g. within Descriptor 1: diversity). Rare and sensitive species are potentially heavily affected by trawling even though the structure and function of a community is largely unaffected. To account for rare and sensitive species, we included a second benthic impact indicator which is more precautionary (L1). This indicator assumes that a population is affected by trawling if animals are disturbed by trawls during their life span. Only species in the community with a longevity less than the average interval between two successive trawling events, based on the swept area ratio, will not be affected (Rijnsdorp et al. 2020).

For both indicators, sensitivity of the benthic community is estimated from the longevity of benthic fauna in the community, i.e. the more long-living organisms the higher the vulnerability. Predictions of longevity, and hence impact, are available for the North and Baltic Sea, based on the present unfished reference condition of infauna and small epifauna, as collected by boxcore and grab samples (Rijnsdorp et al. 2018, van Denderen et al. 2020). The unfished reference condition does not take into account what could have been present in the past. It thus prioritizes areas that are at present sensitive to bottom trawl disturbance and directly benefit from protection.

References

Eigaard O.R., Bastardie F., Breen M.l., Dinesen G.E., Lafargue P., Nielsen J.R., et al. 2016. Estimating seafloor pressure from trawls and dredges based on gear design and dimensions. ICES J. Mar. Sci. 73(1): 27-43 https://doi.org/10.1093/icesjms/fsv099

ICES 2017. EU request on indicators of the pressure and impact of bottom-contacting fishing gear on the seabed, and of trade-offs in the catch and the value of landings. ICES Special Request Advice, eu.2017.13. 27 pp. https://doi.org/10.17895/ices.advice.5657.

ICES. 2018. Interim Report of the Working Group on Fisheries Benthic Impact and Trade-offs (WGFBIT), 12–16 November 2018, ICES Headquarters, Copenhagen, Denmark. ICES CM 2018/HAPISG:21. 74 pp.

Hiddink, J. G., Jennings, S., Sciberras, M., Szostek, C. L., Hughes, K. M., Ellis, N., Rijnsdorp, A. D. et al. 2017. Global analysis of depletion and recovery of seabed biota after bottom trawling disturbance. Proceedings of the National Academy of Sciences of the United States of America, 114: 8301–8306. https://doi.org/10.1073/pnas.1618858114

Hiddink, J. G., Jennings, S., Sciberras, M., Bolam, S. G., Cambiè, G., McConnaughey, R. A., Mazor, T., et al. 2019 Assessing bottom-trawling impacts based on the longevity of benthic invertebrates. Journal of Applied Ecology, 56: 1075–1083. https://doi.org/10.1111/1365-2664.13278.

Pitcher, C. R., Ellis, N., Jennings, S., Hiddink, J. G., Mazor, T., Kaiser, M. J., Kangas, M. I., et al. 2017. Estimating the sustainability of towed fishing-gear impacts on seabed habitats: a simple quantitative risk assessment method applicable to data-limited fisheries. Methods in Ecology and Evolution. 8: 472–480. https://doi.org/10.1111/2041-210X.12705.

Rijnsdorp, A. D., Bolam, S. G., Garcia, C., Hiddink, J. G., Hintzen, N. T., van Denderen, D. P., and Van Kooten, T. 2018. Estimating sensitivity of seabed habitats to disturbance by bottom trawling based on the longevity of benthic fauna. Ecological Applications, 28: 1302–1312. https://doi.org/10.1002/eap.1731

Rijnsdorp AD, Hiddink JG, van Denderen PD, Hintzen NT, Eigaard OR, Valanko S, Bastardie F, Bolam SG, Boulcott P, Egekvist J, Garcia C. 2020. Different bottom trawl fisheries have a differential impact on the status of the North Sea seafloor habitats. ICES Journal of Marine Science. 77(5): 1772-86. https://doi.org/10.1093/icesjms/fsaa050

van Denderen, P.D., Bolam, S.G., Friedland, R., Hiddink, J.G., Noren, K., Rijnsdorp, A.D., Sköld, M., Törnroos, A., Virtanen, E.A. and Valanko, S., 2020. Evaluating impacts of bottom trawling and hypoxia on benthic communities at the local, habitat, and regional scale using a modelling approach. ICES Journal of Marine Science. 77(1): 278-289 https://doi.org/10.1093/icesjms/fsz219

Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0	0	100	NA	NA
5	NA	NA	NA	NA	NA
10	NA	NA	NA	NA	NA
15	NA	NA	NA	NA	NA
20	NA	NA	NA	NA	NA
30	NA	NA	NA	NA	NA
40	NA	NA	NA	NA	NA
60	NA	NA	NA	NA	NA
80	NA	NA	NA	NA	NA
99	NA	NA	NA	NA	NA

Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0	0	100	NA	NA
5	NA	NA	NA	NA	NA
10	NA	NA	NA	NA	NA
15	NA	NA	NA	NA	NA
20	NA	NA	NA	NA	NA
30	NA	NA	NA	NA	NA
40	NA	NA	NA	NA	NA
60	NA	NA	NA	NA	NA
80	NA	NA	NA	NA	NA
99	NA	NA	NA	NA	NA

Baltic Sea

ICES Advice 2021 – https://doi.org/10.17895/ices.advice.8191

Baltic Sea

Summary

Table 1

Figure 1

Pressure

Figure 2

Table 2

Figure 3

Figure 4

Core fishing grounds

Figure 5

Figure 6

Figure 7

Figure 8

Fishing by métier

Table 3

Impact

Figure 9

Figure 10

Table 4

Figure 11

Management scenarios

MSFD habitat - 1

MSFD habitat - 2

MSFD habitat - 3

MSFD habitat - 4

Overview all MSFD habitats

Bothnian area

Summary

Table 1

Figure 1

Pressure

Figure 2

Table 2

Figure 3

Figure 4

Core fishing grounds

Figure 5

Figure 6

Figure 7

Figure 8

Fishing by métier

Table 3

Impact

Figure 9

Figure 10

Table 4

Figure 11

Management scenarios

MSFD habitat - 1

MSFD habitat - 2

MSFD habitat - 3

MSFD habitat - 4

Overview all MSFD habitats

Gulf of Finland

Summary

Table 1

Figure 1

Pressure

Figure 2

Table 2

Figure 3

Figure 4

Core fishing grounds

Figure 5

Figure 6

Figure 7

Figure 8

Fishing by métier

Table 3

Impact

Figure 9

Figure 10

Table 4

Figure 11

Management scenarios

MSFD habitat - 1

MSFD habitat - 2

Effort reduction (%)	Average PD impact	Average L1 impact	Area unfished (%)	Value (%)	Weight (%)
0	0	0	100	NA	NA
5	NA	NA	NA	NA	NA
10	NA	NA	NA	NA	NA
15	NA	NA	NA	NA	NA
20	NA	NA	NA	NA	NA
30	NA	NA	NA	NA	NA
40	NA	NA	NA	NA	NA
60	NA	NA	NA	NA	NA
80	NA	NA	NA	NA	NA
99	NA	NA	NA	NA	NA